I think the key to really getting into the game, is to not ignore any part of the game.
eg. I used to have the same problem. For me it was because, I was only really concentrating on the transfer part of the game. This meant as soon as one window was over, all I wanted was the next one to come along. Now I pay more attention to every aspect, especially the training where you can tweak every individuals schedule, so that they improve on the aspects which you want a player in their position to be good at, but he himself isn't good at. Also focus on hiring a complete backroom staff, try to eventually build a team of 5 star coaches. Put a lot of thought into your tactics. Use the creator first of all, to define each players role as a base for how to play them. NEVER leave it there though, every players settings should be tweaked appropriately over time, so that the team as a collective ends up playing the football you want.
The purpose of all this is that you feel like you've put a lot into the game and will be less likely to want to quit the game.