I've been running for around five months now and I've completed four 5ks, I came in third place the first two times, first place for females/overall second in the third, and the fourth was a race with like 4,000 runners so I didn't really take it seriously, plus I had pink eye and strep throat. I'm starting out strong (I can do two consecutive miles in seven minutes) but then the right side of my abdomen starts to cramp up and that's when I slow down. It's really starting to piss me off. I need to run three consecutive seven minute miles in less than a month and in like four more months I start training for my first half marathon. I'm also hoping and praying to be on the cross country team at school this coming fall. I guess what I'm saying is that endurance seems to be my problem, I start out strong and then I taper off. I'm pretty short for a runner and I could improve my diet but I hit the gym a lot and do a lot of cross training on the side. I have lean muscle but I could build more I guess, I'm more on the slim side so maybe I'm just kind of weak, then again I do train a lot. I was thinking of doing the Insanity work out plus running and the gym this winter but now I'm debating on doing more yoga and biking instead since I seem to hit my best times when I do a lot of yoga, I just want to get stronger. Any tips at all?