Listen, Genos. You just have to keep doing it. No matter how hard it gets. It took me three years to get this strong.
One hundred push-ups! One hundred sit-ups! One hundred squats! Then a 10km run! Every single day!
And of course, make sure you eat three meals a day. Just a banana in the morning is fine. But the most important thing is to never use the A/C or heat in the summer or winter so that you can strengthen the mind. In the beginning, you'll wish you were dead. You might start thinking what't the harm of taking a day off? But for me, in order to be a strong hero, no matter how tough it was, even if I was spitting blood, I never stopped. I kept doing squats even when my legs were so heavy they refused to move. Even when my arms started making weird clicking noises, I kept doing push-ups.
A year and a half later, I started to notice a difference. I was bald...and I had become stronger!
In other words, you gotta train like hell to the point where your hair falls out. That is the only way to become strong.
--Saitama, One Punch Man episode 3