The 24 year old striker, who signed from non-league yeading last year, had hit four goals this season in fourteen appearences, ten as a substitute.
"I have noticed the differences between non-league football and league football, especially off the pitch" the player said.
"You have to look after yourself much more at this level but I think I'm coping with League One quite well."
Campbell is pleased with the way the Bees have been playing this year and beleieves that there is a lot more to come from the West London side,
"We've started well but been inconsistent at times, I think if we play at our best which we have done in patches this year we have a real shout of a sucessful season"