You had a standard you expected of yourself before you had a girlfriend. Now you have one, and in one hand you say you have gained weight and your body is nutcracker different from last year (in a different comment), but you also think you look 'relatively good'. This sounds like rationalization to me, and I don't think you are looking at this the right way. You were willing to work hard to impress a bunch of strangers (in hopes that you would attract one) ... but now that you have someone who loves you, she doesn't deserve the effort?

This is the same kind of thinking where married people don't think they need to feed their relationships... and then wonder what happened to the love and fun times. My ex-husband admitted to me once that since I had stood up before everybody we knew and said I would be his forever, he didn't need to keep me interested like when we were dating. Notice I said ex-husband... because who would want to stay in a relationship with someone who thought love equals no effort.

Based just on your own comments, I would wager that if your relationship ended, you would be plenty motivated to get back to your previous standard.