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.

To put it simply, when you quit, it becomes more difficult to accomplish your goals. Therefore, persisting through challenges can truly make a significant impact.