I've been a gym goer for the past 2 years now, average 3 times a week. I'm 25, non smoker and a healthy size 12 yet I really struggle to run! I've currently just finished w2 r3 and although I've managed it ok it's not as easy as it looks on paper! My breathing isn't too bad but I find my legs throb like they are saying "stop"! I've had a gait analysis and was told my run is near spot on and a new pair of trainers might not necessarily improve anything. Does anyone else really struggle? I see people much older and heavier than me running for ages and I wonder how they are doing it?