Some people experience alertness, relaxation, and a refreshed sense of well being. Ask your doctor if Sleep is right for you.
If you really want to clear out your brain, the best thing I know is hang-gliding, but that tends to take place at inconveniently distant locations.
1) It's got a fairly flat learning curve.
2) The rewards are immediate and gradual, but clearly noticeable.
3) It's relatively cheap, though you can't cheap out on shoes if you are going to run on cement. A good pair usually costs over $100, but you can get them for half the price online if you know your size for a particular model.
4) It's convenient. However, you do need access to a shower afterwards.
5) You can do it alone or with someone else, at any time you want.
That being said, I found taichi to work just as well in clearing the brain, but you don't get the endorphin rush or the cardiovascular improvements as much.
I love cycling - but any bike ride under an hour isn't really worth the time, unless you're doing hard intervals or climbing a really steep hill. If you have 30 minutes, there's nothing more efficient than running.
I enjoy yoga but it always leaves me wanting more.
To each their own, I guess.
Alcohol, coffee, online porn, energy drinks, drugs, cigarettes are all bad ideas.
If you choose to believe ayurveda (the ancient Indian medicine) you need to have equal amounts of "Sun" and "Moon" activities during the day. Sleep, computer usage, reading are all Moon activities. All of us here do way too much of them. To stay in shape we need to counter-balance them with some team sports, interacting with people, running, jumping, playing, etc. BTW, meditation, although it's very effective, is also a Moon activity.
Read "The Power of Now" for a better (and lengthier) version of what I just said.
And yeah, try and take it easy... :D
Some of the meditation methods overlap with deep breathing. You breath deeply by expanding both the bottom of the lungs, the sides of the lungs, and the top of the lungs. You make sure the bottom ribs are expanding. You don't try to force the expansion to the point where you're trying to hold air in like a puffed up balloon, greedy for more.
You cannot force yourself to relax. Consciously relaxing requires you to relinquish control over the muscles that are tensing up while still observing it.
In your case, I would also work on clenching and then relaxing your toes. There's connective and control tissues going from your feet to the jaws and temples.
If you're going to learn how to do this though, you'll need to set aside definite time where the startup cannot intrude. Supposing you set an alarm clock to buzz in fifteen minutes, then within the fifteen minutes of meditation/relaxation, you must allow all of the concerns, worries, thoughts, obsession, guilt with the startup to drift away. Otherwise, this won't work very well. There are people who develop superlative levels of skill in relaxation and meditation; these folks spend as much time and energy dedicated to it as you would to a startup ... so the least you can do is respect it during the fifteen minutes you are cultivating calmness.
I didn't want to discourage anyone from picking up the practice, though. I wanted to point out it isn't a magic pill with an insta-cure, and it will take some time with daily effort before it starts working. Besides, the very first time, I had trouble sitting still for even five minutes.
Just as a sample, try this:
Find a quiet, clean room with a hard floor that you can still lie down on and be comfortable. It should be softer than a hardwood floor, but harder than a mattress. I used a throw rug on top of a carpet. Get a small blanket or a pillow for your head. I used a $5 fleece blanket from the drugstore.
Lie flat on your back, with your arms slightly away from your body, palms-up. As you relax, your feet should dangle away a little, and your fingers should curl up a bit. Take a deep breath in through your nose by expanding your diaphram. Exhale slowly, and listen to your breath. Continue breathing easily. You should settle into a rhythmic pattern eventually. Keep listening to your breath. Eventually you'll notice that your arms and legs are getting heavy, as the tension drains out of them. Your mouth and eyes and face should relax too. Your mouth will probably hang open. It can take a long time. The first time I did it, it was 20 minutes of lying on my back and breathing before I was really relaxed.
Decide in advance how long you will permit yourself to meditate. I recommend 30-60 minutes. While you are meditating, do not think about anything else at all. If, while you're trying to relax, you begin thinking about your startup, or any other problems, stop and go back to listening to your breath.
The advantage of meditation and Yoga over guns or sports or even martial arts is that you can meditate almost anywhere, and mental discipline is useful for virtually everything.
I've found that even out of shape old farts like me can get the same results by simply raising your pulse to about 80-90% of max for an hour or so. If you do this using smart exercise equipment, it does all the work of figuring out how hard you should be working. Somewhere around minute 20 or so I find myself relaxing mentally, although the physical part is a little painful. Your mind begins to wander. At this point, once you're used to it, you can easily slip into a very meditative state. Focus on a point, recite a mantra, relax your mind. This reminds me of the same feeling I had when I ran, except you don't get the great feeling of being outdoors. On the good side, you don't have to worry about dogs, traffic, or slippery roads.
Best thing about all of that is that you get a great endorphin rush when you're done for the next few hours.
My problem is that I'm always trying to hack my way out of relaxing -- using less time, gulping a Red Bull instead of doing my workout, etc. I'm slowly learning that this isn't something you can take shortcuts with, but it's a lesson I have a hard time with. I guess my mindset is that if you can make a computer do something really cool in ten minutes you should be able to hack your body-mind the same way, but it doesn't work like that.
You might want to sing it note for note
Don't worry... Be happy
In every life we have some trouble
When you worry you make it double
Don't worry... Be happy...
Simple, excellent introductory meditation.
But that takes time to build momentum. As at least one great yogi said "water will clean the mind faster than the mind can clean the mind."
Hot tubs and swimming, particularly in natural water (not a chlorinated pool) will get most of the junk that meditation will take care of eventually in a much faster and more expedient way. Oh, and consider a mouth guard when you sleep, so you don't grind your damn teeth away!
I've made it a point to never train when I'm angry or distressed. (People get the wrong idea when they see bruises on my fists and I mention they are from working out on my punching bag). Anger is my default coping mechanism for stress. It is foolish, yet that is what it is. I once did a 3-mile repetition of kata while I was angry, and it destroyed my skills. It took three months to rebuild it back up from the basics.
I did finally find an effective technique for dealing with anger. It requires me to drop everything else in the world and immediately deal with the anger -- that nothing in my life is more important than dealing with it right at the moment. That's a huge investment of time, though it was eventually worth it when I got less angry and required less interventions.
I can see how, if you're deliberately training yourself to relax during martial arts training, you de-stress yourself during training. You also learn how to stay relaxed while stress is applied to you (during free-sparring). And in fact, for this person who asked the question ... the skill in being able to drop into being physically calm and centered would let him unclench his teeth and keep going.
However, as I mentioned in the other reply about meditation -- there are people who dedicated their whole lives to just meditation and relaxation. It is difficult enough to continue training wen you're exclusively dedicated to martial arts, let alone dedicating yourself exclusively to a startup and you happen to use martial arts with the expectation that it will de-stress you ... so that you can continue the startup, rather than developing martial prowess.
I will say this though. I might have learned how to relax from meditation practice, but I learned how to persevere from martial arts. "Keep going, keep playing." That was definitely worth the price.
I'd say it took me three to four years to really start to understand the power and force of relaxation. But even then, people practice these skills for a lifetime and I still have a ways to go.
For me, practice became a solace and timeout. Just stopping from thinking about work for those 6-8 hours a week was extremely helpful. By focusing on the techniques, it became a meditation.
I am having serious relaxation issues also. I'm working a fulltime job and a startup. I have definitely helped me to start running and working out.
If you are at all spiritual, read the book Be Here Now by Baba Ram Dass. It will put things in perspective and calm you down a bit.
Cheers -
http://jadedragon.com/archives/martarts/yiquan01.html
Good luck.
You could also see a dentist to get a mouth guard made.
Also, I find when I get that pressure before going to bed it's a sign that I'm going to grind my teeth. I sit up, give the jaws a relaxing rub, maybe prepare myself for some reading and the expectation that I won't be at work early next day, then have a good sleep.
Also use your fingers to massage the outside of the chin at those times.
Find out the source of your worries and destroy your fear by making those tough choices that you may be avoiding. What are you worrying about if you love the startup? Would you rather be somewhere else? Do you sense something bad?
Also a nice scotch with some Miles Davis in the background works great.