He was the first child of Goku. He was named after his grandfather Gohan. At first he was a wuss. But when Raditz arrived on Earth he unlished his power which was huge for his age and I mean huge. He by doing this weakoned Raditz.
He was then trained by Piccolo so that he could control this power and also to help fight the other saiyons Vegeta and Nappa. But he still did not have enough experiance fighting as seen when the attack on Nappa failed which Gohan ran from and cost his friends dearly. It showed the same lack of confidence as in the Cell Era. He was about to give up when Goku said he was great and that he could do it. That unlished his full potential and then he destroyed Cell.
He also had another problem his mother ChiChi wanted him to become a scholar. So he switched back and fourth between them. He later does become a scholar.