Yes, the difference is that you are creating an external environment which rewards you for success and punishes you for failure. This is similar to taking a final exam, which is my inspiration.

The problem with committing to work rather than success is that you can always just rationalize something as "Oh I worked hard" or "I put in my best effort." However, just as with a final exam, the only thing that will matter in the end is if you actually do what it takes to get the high score. This incentivizes good consequentialist thinking and disincentivizes rationalization.

I agree there are things out of your control, but the same is true with final exams. For instance, the test-maker could have put something on the test that you didn't study much for. This encourages people to put extra effort into their assigned task to ensure robustness to outside forces.