I think the biggest thing that you can change with your body for both sexes is weight. If you are overweight, that's a big problem. There are many people that don't have respect for people that are overweight. So if you want a partner, and you don't have a partner and are overweight, you may want to look into doing a lot of jogging. And don't give me the "well you don't jog" because I'm not overweight and I jog every day. Just some advice for both men and women. Appearance is very important.
I'm not overweight and have had one relationship my whole life that lasted about 2 months. Being overweight isn't the biggest thing. Although I will admit it does play a big part in self confidence. I've seen overweight people get in relationships with real hot people of the opposite sex. It just takes self confidence in one's self and takes inner security. Just my opinion.