Firstly - it's only one sentence, so there is no need for a plural. Secondly - it doesn't really make sense. There should be another verb after stop, e.g. 'stop you making', or something similar. And we typically would not use 'where' with fears either. Where did you find this? Was it written by a native speaker?

The amount of sacrifice you are prepared to pay for human kind.in other words, does your fears limit your courage (acts as an impediment to your commitment and courage)?