A healthy mind in a healthy body is the goal of all but how many of us can find or the inclination to do regular exercise. Not me - yet I have made a routine by which I get regular exercise throughout the day. In the morning while brushing teeth, combing hair, or any other routine work that involves standing for some time, do spot marching or waist rotation (like with hula hoop).
Never miss any opportunity to walk. Although climbing stairs is sternous, never take a lift for going down.
While bending forward or reaching up to take anything, both these actions can be converted to bending and streching exercise if done with the right posture.
If you are reading this then you spend a lot of time before the computer - sit on a straight backed chair - raise one foot 2 inches from the ground - hold for 10 seconds the raise the other foot for 10 seconds. Any exercise done against resistance (gravity in this instance) is more effective.
You can find little ways of exercising individual groups of muscles while doing various daily activities - you just have to be innovative and dedicated.