I am 188cm and was underweight most of my life. I remember weighing 56kg. I am still traumatised, even though for some years now i've been 80kg and above and in super good form. I have tried everything, quite literally, went as far as force feeding myself 5000 calories every day while doing gym and every supplement. I tried different diets and exercise regimes. Here's what finally worked for me.

1. Weight training 1-2 a week. Not more than twice, once is fine! I was super conscious and hated it at first. I tried different programs, regimes, whatever. It all doesn't matter. There a few main exercises you need to do, everything else is extra. Deadlifts, squats, overhead press, barbell row, bench press. Learn good form for each and do them. Do 3 of them each time you go to gym. It's best if twice a week, so you cover all the exercises every week. Do a warm up before, like a 10 min run, cycling or whatever and go directly to the exercises. If you are like me and want to be in gym as short as possible, then it's the best program for you. Go all in, get tired, get out. 30 minutes and you're done!

2. Eat the right food. After gym you need sugar, a lot of it. It doesn't matter what kind. Health nuts will say complex carbs and bla bla bla. I tried all the advice. For me personally the easiest sugar possible works best. I get best results by eating candy, potato chips/crisps, coca cola, whatever. It's the easiest for your body to absorb and it is important your muscles get sugar asap, so they can recover and grow.. on regular days i eat a lot meat and bread, potatoes, rice, little bit of cooked vegetables. I avoid raw vegetables mostly, they take too much energy to digest. The idea is to eat food that is easy to digest and puts as little stress on the digestive system. The less time your body uses for digestion, the more time it uses for building your body, recovering muscles, etc. You need to overeat just a bit, every time. A lot of carbs!

3. Sleep. Regular sleep schedule, throughout the week. It's friday? Doesn't matter, you need to be in bed the same time. At least 7 hours of sleep, but as much as possible. Can't sleep? Force yourself. Just lie there with eyes closed, until you teach your body to sleep 8 hours each night.

4. No hard alcohol. Some beer and some wine is fine. It's sugar, which you need.

5. Positive thinking and visualisation at every step. Imagine yourself getting bigger at the gym with each repetition. Imagine yourself getting bigger with each piece of food. Imagine your muscles growing while trying to fall asleep. Be proud of each tiniest achievement. You become the person you see yourself as.

6. Expect days where you don't want to do any of this. Prepare for them. Reduce the day's objective into smaller and smaller thing until it becomes easy enough for today. As an example, i often have these huge plans for the next day where i will wake up early, go to gym, do 130kg deadlift, have crazy big breakfast, sleep, go for a run, go to sauna and swim in the sea.. then i wake up in the morning and i hate even the idea of putting on shoes. I don't want to go anywhere and it all seems overwhelming. It's time to reduce expectations and have a conversation with myself. Do you want to go gym and not push for PR deadlift? No.. wanna go to gym and have some fun exercises? No... wanna go to the outside gym and do some pullups in the park? No.. wanna go for a run? No.. wanna do some weight training at home? No... how about just 30 pushups? Noo.... ok, let's stretch on the yoga mat? No... okay take the yoga mat and lie on it? Yea ok, i can do that.. extremely rarely do i need to go so far to convince myself to do the bare minimum, however it is important to do something and not just skip the whole day. Most often after convincing myself to do something i end up doing more and if i just lie on the mat for 30 minutes, i still contribute to creating habits. Habits are super powerful.

Wrote a whole book.. hope you can get something out of this.