When I entered college I was 6'0 and 155 lbs, a wiry 18 yr old soccer player. By the end of my freshman year I had gained the "freshman 15" in pure muscle, sitting at 170 lbs. At my heaviest I was nearly 195 lbs, which was between my junior and senior year, about 21 years old. So how did I average around 10 lbs of muscle growth year on year? Well first I knew my goal was to get bigger and stronger so the people I surrounded myself with were of the same mind set. 4-5 times/week I would meet up with guys at the campus gym and body build. Unlike me half of these guys had played football in high school so they knew how to lift and build a program of progressive overload. I had taken some weight lifting electives in high school but being a soccer player, weight lifting was never a requirement for me to get good at. To this day thats some of the best advice I can give to anyone wanting to build more muscle. Link up with people who know more than you and don't be afraid to ask questions or try new things.
My workouts were push and pull, upper and lower body days for the most part. After a warm up, I would generally do sets of 12,10,8, 6 reps for my compound barbell lifts. I might throw in an extra set here and there as well. Following the barbell work, I would do dumbells for 10,8.6 reps. I might also change the angle of the lift, for example, I would follow barbell flat bench with incline dumbbell bench press or following barbell squats with dumbbell split squats or walking lunges. My third exercise consisted of an isolation movement, tricep extension, skull crushers or dips, or after squats I would do leg extensions for example. I usually was down to do a burnout or drop set of anything at any time in my workouts, for when you are lifting with motivated people its easy and fun to push each other to your limits, AKA to failure. This might come in the form of push ups with plates on our back with no break between sets. We would do as many as we can then lessen the weight and repeat until you have no more weight on you and you can't do any more.
By the spring of my freshman year, I had essentially walked on to the soccer team for the school which was a D1 program and required you to attend daily weight training sessions early in the morning. I excelled at these sessions because I was more experienced in the weight room then most of the other freshman. However, NCAA life wasn't for me at that time and by my sophomore year I was playing club rugby for the school. I prefered this sport and lifestyle much more and also enjoyed being able to workout when I wanted to, which was at night. I found that I was stronger and was able to lift much more at the end of the day than I was first thing in the morning. I attribute this to the fact that I had been storing energy by eating all day. Verses when I liftted in the morning, I was coming right off a fast, (sleeping).
Other than working out, diet is even more important in achieving weight gain. I was lucky enough to have an unlimited meal plan at the school cafeteria and so I took full advantage of that. I was eating 4-6 meals/ day, plus a protein shake, (I never took creatine until I was well out of college, 7 years later). I would eat 3-4 eggs in a veggie, ham, and cheese omelette in the morning, sausage, potatoes, yogurt, oatmeal and fruit were also common in one sitting. I loved milk, so I drank skim milk in my cereal in the morning and a tall glass of milk at night. I loaded up sandwiches and salads with every meat ,veggie and sauce that they had. I ate mashed potatoes, chicken, beef, pork, fish, mac and cheese, burgers and whatever else they were serving as the main dish that day for lunch and dinner. I never left the cafeteria without getting a large panini sub to go so I would have those to eat as a snack.
I did notice the more running I was doing to get in shape for rugby, the harder it was to gain anymore weight, my body has a very fast metabolism naturally and I believe that we all have that point in our weight gain goals that's going to be hard and even unnatural to surpass. However, to this day, as long as I keep going to the gym a few times a week and eat 3-4 meals a day I will keep most of my muscle mass, which looks like 180 lbs. Essentially, now I can do half the amount of work I use to do to maintain what I built up, which is nice. I also still do lots of cardio-sports weekly, like surfing, rugby, and jujitsu.
This goal of a built, muscular physique is achieved like any other. You have to work hard, collaborate with like minded people and learn from those who know more than you, stay consistent, always push yourself to be better no matter how much better you have gotten, and be willing to do it for years. That is how I achieved my physique goals and I believe its the same blueprint for anything you want you achieve in life at a high level.