1. Total body workout for 45 minutes - you need a good yoga mat to protect your knee/back -> youtube, pick 2-3 different videos from different "instructors".
> If it has to be something like pushups it at least has to be a routine simple enough so I don't have to watch some fitness dude or gal on youtube and follow them. I'd rather watch or listen to something interesting in that time.
I tried doing fitness and have my mind somewhere else: didn't work well. Don't fight it, listen to what they say, focus 100% do it right so you can learn what muscle is targeted for which exercise and to avoid injury as well.
> any science based plan on how or what I should train?
Most trainings are science based.
Get a dumbbell (buy 1 pair) or kettlebell (buy 1 piece), expand your total body workout to include a little bit of strength training.
2. Run 5k/10k - you need good running shoes
Yes, it's boring, but the journey from couch to 5k then figured out how to reach 10k, has been a great challenge + journey + accomplishment. Learn how to run correctly. Learn how to reduce toll on your body via different training methods.
3. Cycling - yeah, it takes time; time well spent in my case
Sign up with strava. Track your metrics. See if you can climb higher elevation. See if you can bike longer/further. Plan your route. If you can do 50k with some hills, can you plan 70k without hills? All these planning is fun for me.
Personally exercise takes my mind off from routine works (regardless if you're doing R&D or CRUD app: they're the same, there's a pattern and routine even in "exciting ML research").
I feel relieved/recharged after a 5-10k run session or a long bike ride.
I enjoy the process c25k (couch to 5k). I enjoy the process to move the goalposts to hit 10k. I love that feeling of achievement too.
I realized that running 5-10k regularly requires me to take care of my body: sleep + nutritions + muscle building (this is why I do total body workout + strength training).
I acquired new sets of skills/ways of thinking from all these exercise.
Just like software has technical debt. Our body needs to be maintained as well.
I love/enjoy the journey from not knowing about fitness in general to where I am today. Fitness becomes my hobby aside from software development and I'm happy that I chose to invest in myself.