Help for Committing to Health

It doesn't matter how many new books or exercise DVD's I buy, I can't seem to get myself to commit. To anything.

I talked to my therapist today, and he said to try to make small goals (kind of like the Just for Today I Will ___) thread. There's an issue though: I can't think of JUST "this one day." I constantly just think "yep, I will have to do this for the rest of my life," which translates to "but I can't imagine I will FEEL like doing this for the rest of my life". It feels like extreme laziness, but it's obviously mixed with depression, as well as believing that nothing I do (exercise, eat right, etc.) is ever going to work because I have failed so many times before. I just obsess on the past and future, I suppose. I've been like this all my life.

Anyway, for those of you who have recovered from similar thoughts, what was your turning point? I mean, I've been trying to (or reading up on how to) lose 20 pounds since I was 12 (I'm 20 now), though in the last few years it has moved up to 30. I think I know a lot about eating well, fitness, etc...

But I never put any of it to use.

While the thoughts themselves are ridiculous and lazy, am I communicating this effectively?

I will say this: Once I start doing one of the necessary steps to losing weight (by exercising, or even eating a salad for God's sake), I love the high I get from it. The only issue is that I have trouble keeping a pattern of it.