The best exercise is one that you enjoy and will do. But otherwise … it’s probably running. Running is cheap, easy (as in you go out of your house and just do it) and you can’t fake it – it’s always energetic. Even a jog counts as moderately vigorous exercise.
If you are time poor, you need run for only half the time to get the same benefits as other sports. Angelique Brellenthin, of the department of kinesiology at Iowa State University, one of the review’s authors, says it takes 105 minutes of walking to yield the same benefits as a 25-minute run.