For me, there are two aspects to it: (1) Make your diet decisions at the grocery store to remove temptation at home. (2)Find exercise that you think is fun. I

For me, there are two aspects to it: (1) Make your diet decisions at the grocery store to remove temptation at home. (2)Find exercise that you think is fun. I personally can't run for more than 2-3 miles without getting incredibly bored, but hiking for 30 strenuous miles over gorgeous terrain is enjoyable. So too is chasing a little black ball around a squash court or running after a frisbee. Each person will enjoy different kinds of exercise, but once you find the one you like it'll turn "having to exercise" into "getting to go _play_ <x>".