well it doesnt make your lungs stronger for athletics, but it really hasnt impacted me as an athlete and i smoke daily. even as a daily toker, i have an athletes blood pressure, and great stamina. all you need to do is stay active and keep excersizing, and the weed wont affect you as much. all my friends that smoke but dont play sports are in terrible shape, but those stoners that keep active seem just fine. i wouldnt worry about it man.