C.D.
If he can do it, let him. My son has refused to go in the stroller since he was about a year old - insists on walking himself. He now often goes more than a mile at a time. If he gets too tired, we stop and rest, have a drink, then continue when he's ready. My take on it was, he'd have a good healthy exercise habit, and it was all his choice - a good way to build a healthy relationship with his body as he grows up.