I've seen some weirdly misshapen swimmers who were amazing swimmers. your choice of activity isn't what matters. what matters is your compliance and style. anyone can waste time doing anything. also, you're too late to lose weight for the summer. plan ahead and get into a routine now so that next winter you can lose weight for next summer. I would suggest alternating between running; swimming; cycling and weight training. if you're not motivated don't bother. be patient. day by day; week by week; month by month; year by year you will improve and see results. don't give up even if you have a bad day; week; month or year. I'm in the middle of a horrendous year and am really depressed but I'm not giving up.