If you eat ice cream frequently, buy a heavy spoon.

It truly depends on your goals. ex: cardiovascular fitness, strength, mass, cut/toned physique, explosiveness/quickness, etc.

To quote an acquaintance: "change your diet for weight goals, change your training for body composition goals"

As a very rough direction, I would advise you to follow a well-established and respected program for training, and avoid anything and everything processed for foods.

I personally follow the Starting Strength program (a compound-lifts program designed for beginning strength training) & GOMAD (gallon-of-milk-a-day) for diet. I have had excellent results with respect to my own goals.

learn the basic compound lifts with a barbell - squat, deadlift, bench press, overhead press, clean, and row

learn a routine and stick with it - some suggestions are:

mark rippetoe's starting strength (http://aasgaardco.com/store/store.php?crn=199&rn=312&...)

westside for skinny bastards (http://www.defrancostraining.com/articles/38-articles/60-wes...)

bill starr's 5x5 (http://madcow.hostzi.com/5x5_Program/Linear_5x5.htm)

you'll get more bang for the buck out of a real weight lifting routine with some added cardio or barbell complexes (google the cosgrove evil 8) rather than a mostly cardio based routine. cardio by nature is catabolic - it is nearly impossible to maintain muscle mass while training cardio heavily. instead, focus mostly on lifting weights to alter your body composition (build muscle, improve posture, burn fat) and using cardio to supplement that with increased endurance and overall cardiovascular health. the optimal cardio to pair with weight training is HIIT (high intensity interval training) - basically sprint training. if you need any reason for this, compare photos of a marathon runner with a 100m sprinter and you'll see the obvious differences in body composition.

if you want to look like an athlete you need to train like one, period. fitness should a complete lifestyle change, not a weekend hobby.

I find anything that lets you zone out is a great physical activity. Granted, I'm not a battle-hardened entrepreneur.

Martial arts are great, if you know a weapon or specific technique you love. Nunchakus are great, but make sure you mark them as wind chimes for legal reasons, if you use metal ones. It builds everything. Carido, strength, dexterity, and even pain tolerance. I'm teaching a course starting September - if anyone is in London, ON, you're welcome to join.

Experiment, and find out what works for you. Everyone's lifestyle, environment, genetics, and goals are different, so your workouts and diet must be tailored to fit you. While there are general principles that are true most of the time, there is no one-size-fits-all workout or diet.

The exercise of experimenting with one's lifestyle and seeing the effects may be fun in it of itself.

I just go rock climbing a lot.