Strength is a skill in the way that hitting a baseball far is a skill, or boxing. Being big and hitting big do not correlate all that well. The same goes for judo and jiu-jitsu, where leverage and technique are king. Of course size helps, but it turns out that coordination counts for waaaay more.
So there are ways to “learn strength” without adding meat to your frame. Why do that? Maybe you are a runner or gymnast, or you do not want to buy a new wardrobe, or you want to stay within a weight class. Once I saw the West Point rugby team play and remarked that their players were much smaller than ours. It was explained that the cadets were required by the Army to stay within a prescribed weight limit. They were not allowed to inflate themselves to mountainous sizes at the squat rack.
Also, learning “skinny strength” is easy and comfortable, both physically and mentally, and so it is wonderful for lazy people like me. You just practice your skill as often as possible while staying as fresh as possible. You must stop long before you get fatigued. Don’t you love that? To succeed, you must avoid working hard! In fact, you will not even do a “workout”—remove the word from your vocabulary. Seriously. What you will do is a practice session. If you were learning a language, you would learn better and more happily in 15 minutes a day than in a single 2-hour slog each week. This is no different.
For fun, try the “ladder” method. Say you can do 10 pushups. Not bad! Get down and do one pushup, then take a short rest. Now do two pushups and take a short rest. Then do three pushups. And stop there. Take a longer rest and repeat the “ladder”: first one pushup, then two, then three. Repeat that sequence, with ample rest, until you get bored or you feel the first whiff of fatigue, and then stop. It will take only a few minutes and make you feel peppier than when you began. Do that once a day for a week (or better yet twice a day, as long as you stop well before muscle fatigue), and then take a day off and test your pushup max again. You will BLOW AWAY your old number.
You can use these “ladders” easily for exercises like pushups, pullups, crunches, and planks—where you’re trying to increase reps or time—and it’s so simple that you can probably teach rodents and ultra marathoners to do it. (Just kidding, ultra runners! I love you guys! I just don’t understand what drives you.) For higher primates like the rest of you, there are also simple tweaks that let you apply it to pure strength exercises.