I am getting back into exercising after a long time of inactivity. My main concern is not building muscles for a bodybuilding contest, but building up muscles for endurance and stamina. I cannot afford a gym membership at this time. But we have walking trails around my area and some old 15-20 pound dumb bells in my garage. Any ideas on a good exercise program with those? I want to be able to carry a bug out bag several miles if need be if I have to abandon my car in order to get back home. Thanks in advance for any advice.