Short sets of bodyweight exercises like push-ups can build the strength you need for a longer life.Courtesy of Christopher Sciamanna/ milan2099 via Getty ImagesExercise is one of the best longevity tools we have, and most of us don't get enough of it.A doctor said doing a few minutes of daily exercises like squats and push-ups can have big benefits.He shared his full-body workout routine for a longer life in less than 30 minutes a day.Dr. Christ…