In high school I would lift everyday and see no gains whatsoever. I was just going through the motions. Most people work out this way. In college I started lifting with extreme intensity--every single lift, red faced, sweating, straining. I gained about 25 pounds of muscle and never lost it. You need to get angry, pissed off, amped up. Whether you are trying to gain muscle or lose weight, this is most important. This is hard work. It's not for pussies. It's not social hour. You are going into battle; you are literally tearing your muscle fibers in order to build them back up. People forget that. Listen to 50 Cent on the way if you have to. Pretend you are an athlete in training. Enjoy the suffering. Get angry at all the things you could have done today, this week, this year, this life. Why aren't you living up to your potential? The world gives us plenty to get angry at: poverty, world hunger, texting while driving, politics, apathy, cheating, lying. That's the righteous anger that propelled Gandhi and Martin Luther King Jr. I'm not the guy who grunts and throws weights around, although in my head that's exactly what I'm doing. I feel alive in the suffering. I am Jesus and Gandhi. It's like running a 5K: a slow death that ends with the most exhilarating feeling of accomplishment I've ever had.
This is going to be hard at first. When it comes to practicing virtue as opposed to vice, everything worth doing is hard at first. It will take a few weeks (not days) for the body to get used to the soreness and for the mind to get used to the intensity. Will power leads to habit. As David Hume habitually repeated, we are "creatures of habit"; and that's a beautiful gift from God (Hume wouldn't agree with that last part). Now when I go to the gym I automatically exercise with the same intensity as I did in college. It's a beautiful thing. My brain is dialed in. I cannot have an easy lift or an easy run. If I do not exercise for a week, I get withdrawals. I look forward to it and love it. I am in the best shape and health of my life.
Perfect FormWithout perfect form (i.e., watch your spine) you will get hurt; especially when you are lifting with intensity. In college I hurt my back a few times because I lost form, which still affects me today. For each lift, learn what the correct form is and stick to it. Only do as much weight as you can do with perfect form. Simple as that. And do a warm-up; stretch or take a short run.
There are no secret programs, secret exercises, or secret supplements (except protein...if you want to gain muscle, your body will need more of it). But to me, focused intensity is the only secret.