C.M.
Take him outside once a day. Try taking him out at the same time everyday. Take a walk, throw a ball around, get him a toy to ride in/on. My daughter loves her little tykes car and her fisher price lion! Stay out for 30 minutes to an hour. This will wear him out. Plan it for before a meal and bedtime. Stick dinner in the oven, go play outside. Feed him, bathe him and put him to bed, or feed him take him outside and then put him down for a nap.
This will help establish a schedule for him.