In shape

My boyfriend is extremely into fitness and I on the other hand am not. He goes to the gym faithfully. When we met I was thin and he was too. He started because he hated being skinny and wanted to build muscle. Now he just goes all the time. Needless to say, since we've met, I've picked up a lot of weight. 30 pounds of it while he's been getting fit. I look back and wish I started on this journey with him because I was a whole lot more active then. Well now I'm really self conscious about my body image.. I thought about us going to the beach for vacation and immediately thought of the weight I've picked up. He likes it because I have curves and I do love my booty, legs, and thighs. But I want to tone up my body a lot. Abs && muscle definition. Especially when he's beside me all muscular and chiseled like he belongs in a magazine or some shit. So I tried to motivate myself and work out today with some workout video on YouTube. Honestly I couldn't even make it past 10 minutes without nearly passing out and feeling helpless. This happens so often with me trying to exercise and I just feel so discouraged like giving up. But then I feel even more bad that I gave up on myself and I go eat which is counter productive. I just hate feeling this way. I eat well but I'm still overweight.  How am I supposed to get fit when I can't even last working out ?? What's wrong with me ?