Dating someone more fit than you?

So I was asked out by a guy who is really fit. Like, he has abs. Now, I'm not overweight, and I've learned to love and accept my body the way it is, so I'm comfortable with myself for the most part, but I'm nervous about what he will think of me since I don't work out. I mean, I eat well, and am healthy other than the fact that I'm not very active. I just. I don't know. This is the second time I've ever been asked out and the first time ended up in disaster. I just wondered if anyone could give me some advice.