Fathers of Pregnancy

Options
I hear it all the time. Fathers become 'vacuum cleaners' during pregnancy. My wife is currently 11 weeks pregnant, and I've been eating so terrible lately, that has led to some unwanted weight gain (less than 5 pounds). I don't want to get into the same boat as I was before, and it just seems so 'easy' to eat the fast food or eat what she doesn't. Are there any other fathers out there who experienced this? What did you do to overcome?

I joined a gym yesterday, and I guess self-motivation is harder to come by. Any words of encouragement would be great!