To stay fit in work, one should adopt learning/unlearning/relearning schedule in all models. Let it be work, in relationship or in maintaining physical activeness. Shed old habits which are not current. Be fresh in mind accept latest trends. Keep some physical activity along with being mentally free and fresh. Your openness, reaching quality and pursuit attitude in knowing things will always keep you fit in your work.Never worry but always be happy. This will definitely keep you fit in your work.
just relax a little,walk for 15-20 minutes. while walking keep eyes and ears open and withdraw yourself from other senses. listen to chirping birds,whisteling wind,visualise art in concrete jungle.come back and relax for a minute or so. Then lie down and close your eyes.listen the inner within.take a glass of water and sit for say 10 minutes and meditate, no regulated pose. just fix your eyes on an object, from the distance take the shape unto you.you will feel a light radiating you. then start your day. while working take a little break in between.speak only when necessary. walk in the room for a minute, wish your colleagues. look at them with intense sympathy. avoid tea, smoke and when you feel tired drink a glass of water,feel water passing through your tract and work leiseurely and find the result. afterv2-3 hours take intermittent deep breath and inhale the smell of the surroundings. feel the colours seen,may be they are dull wall paint or even white,invoke the sounds heard and you will find yourself fit enough to work 12 hours a day.
Best thing is learn and keep practicing spiritual sadhana ie meditation. Self awarness is root of all health and intelligence. Most of hollywood star does some or other buddhist meditation see how shining and beautiful they look. Ego consumes most of energy and causes diseas. More u do practice, more u r aware of how your ego is consuming all your prana, vital force. that much more healthy you will be. Thats why i always promote vipassana, sudharshan kriya, osho meditation, land mark forum. They are all excellent technique. Its life long spiritual journey, a lot of hard work. there is no short cut.