seems to have some interest in girls secretly He likes golf and tennis
There you go! Motivation abounds. The trick is getting him to see himself through the eyes of potential girlfriends, teammates or coaches. What kind of shape would they like to see him in? In what kind of shape would he be most proud presenting himself? What's the gap between where he is now and where he'd like to be? What would it take to bridge that gap? How much time can be budgeted for the activities required to bridge it? What current activities might be getting in the way by either using up time that can be spent more productively or actually working against his desires? If he puts his mind to it, I'm sure there are plenty of things he could be spending his time on, even in his current condition, that would help him to move ahead with some aspect of these objectives. Try to keep him focused on reasonable and achievable objectives - both short- and long-term. Help him to understand that none of this is going to happen overnight, but, with a plan of action and some modified priorities the goals can be achieved in time.
Tennis is a very aerobic sport and one that would be great for him to be involved with, but I think you should also encourage him to get involved in something more team-oriented. Having teammates who want and need you to perform better is great motivation. Golf can take a toll on people with strong healthy backs - lots of back injuries from that game - that one might have to wait for a year or so. How about soccer? Lots of cardio and team-orientation. Tickets to professional games are a lot cheaper than those to more popular sports, too, so it's easy to set his sites on some high-level and approachable role models.
