The reality is that I am not really out of shape, I am in the same shape I was 7 years ago and when I was getting married- that was my early twenties... but with that said I want to emphasize how important it is to stay in shape.
Mix up your routine, don't go to the gym and do the same activities. Push yourself. I also took up running and LOVE IT. It puts a tole on your body but man does it feel awesome. I took on Zumba which is sooo much fun and am now mixing it up with different classes. I am not a skinny minnie, I have to work hard to stay in shape, I always have. I do not have the luxury to eat what I want and not gain weight. I always had a small weight problem but I found a program and a lifestyle that works for me and once you yourself finds that program that works for you too you still need to work on at it.
Don't give up, staying in shape is so rewarding to the mind, body and soul. We only get this one body, in this one lifetime...so be good to it, be true to it and stay in shape.