***WALK EVERYWHERE AS MUCH AS YOU CAN, AS OFTEN AS YOU CAN.*** Best exercise of all, if regular and substantive. Gets you to see the sights and people and sounds, smells, etc. Plus, definitely the best general exercise for your money. Walk quickly, through and around crowds, over, through and around street obstacles. Walk with purpose, challenge yourself to be on time, adjust your speed, etc. Great for the brain, as well! Improves foot-eye coordination, muscle tone, stem cell production, agility, endurance, visuo-spatial ability, planning, analytical speed, even predictive analytical ability (watch out for that double stroller!) For slightly more intense exercise for the creatively lazy/"on-the-go professional" , stick with basics - push-ups, sit-ups, pull-ups, or some combination of the three.
For a scientific, 7-minute workout endorsed (or at least discussed) by the NY Times: http://well.blogs.nytimes.com/2013/05/09/the-scientific-7-minute-workout/?_r=0
When you're sitting down, constantly monitor your posture. Sit upright as much as possible. Adjust your seat and/or screen to help with keeping up your posture.
Suck in your gut and hold for 30 seconds while you're sitting. Repeat as regularly as you can.
Stretch regularly. Get up from your seat to do it. Even better, take a walk to stretch. Stand with legs out so you're planted firmly. Bring in the arms and then swing them out along with your torso to the right, then left. Back in the center, stretch out the arms out and up, out and up. Stretch your neck by swinging your head right, then left, 5 times each, then up and down, 5 times each. Stand up on your tip-toes, stretching your calves. Go up and down 5 times each. Repeat this every 45min-1 hour throughout the work day.
***REMEMBER, SITTING IS SLOW DEATH!!*** Move now or earn heart disease, diabetes and other wonderful diseases.
Lean yogic breathing to boost blood oxygen and productivity: http://life.gaiam.com/article/1-minute-breathing-exercise-energy-and-productivity
MANAGE YOUR STRESS EFFECTIVELY (see previous post on Stress Management). Exercise can be quite helpful with this - blowing of steam.
Manage your expectations effectively - expectations of other people and of yourself.
EXERCISE YOUR MIND regularly and for life. In many ways as important for your physical health to keep an active and eternally curious mind.