Hello ifra,
... to reach the goal is hard work and determination. However, others argue that there is another factor behind the success
Your background seems to less paraphrase the question. To paraphrase it I suggest to you :
1. Change the sentence into passive forms:
Hard work and determination
are believed by some people ...
2. Then, Try to find the synonym:
Tough effort and resolution are believed by some ...
... key to success while , SO an obvious schedule board ...
3. While is used usually for contradiction. However in your sentence is not kind of contradiction, because you add some details, so you can change into above words.