How would you reword this sentence to make it easier to understand?
In other words, giving up results in goals much harder to achieve, thus persevering really makes a difference.
First of all, it's not a complete sentence without a main verb.
Next, try something like this:
It's better to ... than to ...
I can't use contractions or "to be" verbs in my essays.
I don't understand what you're trying to say in that sentence.
Persevering brings more satisfaction than giving up your goals.