I am about 1.9 meters tall and very thin. I'm not fat when I eat anything. How can I be strong?

I used to have a colleague who worked hard to gain weight and gained 20 pounds in three months. No matter how he eats, he is not fat. It's no use just eating. The most important thing is to eat more protein, cooperate with exercise, and exercise properly. If you exercise more, you will lose weight.

My colleague is, eat more than three meals, and then do push-ups at home at night and pull my arms. Do it more than 100 times a day. Then, the most important thing is to eat more protein, and then cooperate with proper fitness exercise, so that muscle grows instead of fat. Getting fat is not the goal, but getting strong is the ultimate goal. Come on! Ask again if you don't understand.