Btw, if you have trouble gaining muscle, try the following simple program.
Session 1: squats, bench press, deadlift, biceps curl, triceps kickback, calf raises. Aim for 6-8 rep maxes. Do 5 sets of each.
Session 2: squats, military press, row, lateral raise, leg extension, ham string curl. Again do a 6-8 rep max and 5 sets of each.
Session 3: squats, bench press, deadlift, weighted back extensions, weighted leg raises, calf raises. Do 2-3 sets of each, 6-8 rep max.
Try it with 2 days of non-weight training in between and go ahead and do cardio, swimming, hiking, cycling etc.