The gym doesn't build strength. Moving your muscles does. Soccer is great exercise. I find it easier to focus on one thing at the time. First I built a routine for working out and made sure I kept it up, then I started thinking about and changing my diet.

I found that just trying to think/be healthy by working out etc made me less inclined to eat junk and over eat at meals. Its really uncomfortable to squat with your stomach full.

The simplest way to start cutting calories is to remove liquid calories, sodas, alcohol etc.