I'm 5'11", 165 - 170lbs and always been the skinnier guy in the group. As far as running the mountains and packing out meat it's only put me at an advantage over the 250lb+ dudes I hunt with. I end up carrying the heaviest pack most times. When I was able to put on weight about a year ago I was nearing 190 but I was putting in so much time in the gym and timing so many supplements that I was miserable, and realized the time and effort was not something I was going to look back on and grin. Not only that but my field performance started to suck because my body just isn't metabolically efficient in that state...lots of extra mass that your respiratory and circulatory system has to adapt to/support. My time in the military and being marginally obsessed with my fitness has shown me that as a hard gainer, I'm going to have to basically agonize about it constantly if I want to put on the lean weight that I dream about. I've done it before, several times but I just don't enjoy the gym at all, and with a family, kids and many active hobbies outside of the gym, I've given up on getting "buff". I spend about 30 mins a day doing cardio followed by moderate lifting, mostly compound movements for another 30 mins, 3 to 5 times a week. My excuse to lay off that is when I'm hunting, hiking and snowboarding....lots of natural protein, no bread, and I've learned to be happy with my weight. Sucks for us bean poles!....But I'm glad I'm not constantly fighting getting fat too.