A good way to gain mass

My dad used to be a personal fitness training. His career in this field started already when he was very young. One of his sports teacher saw some potential in him during classes, he advised him to get to some sports-connected studies to get educated in this area further ahead. He managed to do that even despite the times being not perfect then in our country. Anyway, he got a specialty of a fitness trainer. His body looks close to perfection even up to nowadays, which my mum is very satisfied with. Lately we had a conversation with my father. We touched the topic of workouts at the gym. I wanted to know how to gain mass as quick as possible. He gave me some advices, mainly connected with eating. Now I know that the system and scheme according to which we eat is one of the most important things when it comes to the outlook of our body and the health condition too. It is not easy to gain mass in a way that would not trouble the organism in any way. Dad told me that he is eager to prepare a special, individual program for me to help me gain mass successfully. He says that many tries of gaining mass end up with nothing, people do not have any clue how to do it and in this way they sometimes end up with the so called ‘jojo"-effect. Now it should be simpler to me than many other people to reach my objectives, mass objectives so to say.