Hi...I have the same problem. My husband has been steadily putting on the pounds. He was 140 lbs. when I met him; we have been married for 19 years and he is now 220! His health is very concerning to me (had high cholesterol and triglycerides at last check); he knows he needs to do something but his motivation is marginal. I gave him a workout game for the Wii that is pretty comprehensive; he liked it a lot but has been so busy lately that he hasn't used it. So I am stumped along with you.
Maybe you could suggest that your hubby get a physical; it might be that the numbers that come back and what the doc says are motivation for him to get started. Just keep doing what you're doing for yourself, cooking healthy food for meals and having healthy snacks around. Depending on where you live and the weather, you might ask him if he wants to take a walk, a hike, or a bike ride with you, if any of those appeal. How about a pick up game of basketball? Think about what he sees as fun and try to work with that; he might be more likely to get involved.
At the end of the day, though, just remember, he needs to take responsibility for himself, just as you need to take care of you. You can encourage him, but unless he does it for himself, it will just frustrate you both. Hope he gets a jump start soon!