It's both. You need to personally believe it's important for it to stick, and you have to train yourself to keep it in mind. It has to become like a demanding girlfriend you have to remember to txt or call. You can't dump her because she's loaded and you work for her dad.

The right system is totally secondary. It can be as simple as a note in your front pocket. In fact, a written note is good because you have to continually rewrite it, and that makes the tasks stick in your head. It also becomes a huge hassle to keep writing down the same things instead of getting them off the list. When I have to kill my list I do this.

Day to day I use google tasks (iphone-dock and firefox-sidebar) and it stays in my face all day between those two.

A long list is good. There's nothing that guarantees failure in todo world like having tasks like: "Profit". You have to break everything down to the smallest particle you can, then you knock off more things more often and you get used to using your system.

Determination is the most valuable skill in the world, stick with whatever you do and it will pay off in every aspect of your life.