My bike's brakes don't work well.
I had a skilled cook make food for me today.
Koichi is a pretty flexible man.
You know the kanji means profit. When you make it into a verb, though, it means to work well. If you think about it, when something works well it makes you a profit.
What works so well? Your special key (き) that can unlock anyone and anything's potential. Imagine putting it into a key slot in someone's back. Someone who's a good for nothing can't-do-anything is now an effective member of society! Go around using your key on other non-effective things and show them that anything is possible!