Find a sport you like, and do it a lot. Try to get good at it. For me, it was ice skating, and eventually I started figure skating. Figure skating takes a long long time to get good, and you need to be in shape to do it. I want to be good. See where this goes?
When I first started ice skating in March, I was 215 pounds, now I'm 180, and my blood pressure went from 150/90 to 115/45, and I dropped 4 inches at least in pants waist sizes. Even my shoe size went down like half a size or so.
If you're doing something you like, it's easy to motivate yourself to take the steps to get better at it. For me also, it took me doing "free" things to lose weight, like drinking water instead of soda, that sorta thing, but losing weight I knew would help me do what I wanted to do, that's why I even cared at all. If losing weight or having a better diet won't help you do what you want to do, you won't be very motivated to do it. Losing weight, for example, wouldn't help me terribly much for just my daily going online all day or something, so I didn't care to lose weight. If you're doing something athletic, though, you'll find that smoking cigarettes and drinking beer and soda all the time won't be advantageous for you.
Just start something, no matter how silly it seems, just try something. I mean, if someone told me in March my trip to the skating rink on a whim of "man, I haven't been skating since like middle school..." would go this far, I'd have laughed in their face. You don't know until you try.
That's my advice, find yourself a more immediate motivation and push yourself to accomplish that goal, and then things will fall into line more.
For me personally, though, I believe God helped an incredible amount, not really anything like, feeding the 5000 miraculous, but it's still really cool. Maybe the whole "Acknowledge him in all your ways, and he will direct your path." I find it funny how Christians profess that they have faith of eternal salvation of their souls, but don't trust God to help them in trivial matters.