I really struggle with exercise. I have a nerve injury which I got through childbirth and have been struggling with for 4 years. My diet is quite good now, and I've lost a fair bit of weight. I really want to get fit but the only thing that doesn't leave me in pain is swimming. If I swam for about 30 mins non stop 4 or 5 times a week, would this be enough in conjunction with a good diet to get fit? Don't want to become an Olympic swimmer, but would be nice to be able to run for a bus without feeling like I'm going to suffocate!