Systems are a really great way to make things happen. For the past few years I've shunned them, mainly to rebel against routine and revel in spontaneity. If I'm honest though, much of my success has come from well-executed systems.
The earliest thing that comes to mind are the personal systems I devised for studying in school. I didn't call them systems. They were just things I tried that worked well for me. In eighth grade English class we had monthly vocabulary tests. To study, I divided a sheet of paper into two columns. The words went on the left side, definitions on the right. I would review this sheet of paper until I could recite each definition by looking at the word AND tell you the word simply by looking at the definition. This technique left me more than adequately prepared and somehow I was the only student that aced every vocab test that year. Just about the only thing I didn't anticipate was my teacher embarrassing me at lunch one day by bringing me a cake and balloons to celebrate my achievement in front of half the school. Shout out to Mrs. Evanson for doing something really nice that I didn't appreciate at the time.
Anyways, the point is that this system allowed me to flourish (and that I'm way cooler today than I was in junior high). You can use them for personal finance, athletics, really just about anything. They are sometimes tedious by nature, but what I've realized is that you can choose to think of them as enablers instead of boring, repetitive tasks. And there's a certain creativity involved in designing them. I think you'd be hard-pressed to find successful individuals in creative fields that don't use any.
If you are still having trouble justifying their use, think of systems as assistants. Once you've got one in place, they become fairly automatically and free up your energy for what you enjoy doing most. You probably shouldn’t call them systems either. That’s boring.
Got one to share? I'll show you mine if you show me yours.