"It won't be easy - pre-season never is - you have to graft through it and you will reap the rewards.
"Even though it's hard work I'm just happy to be back out there after being injured for such a long time, happy to be running and happy to be back to normal."
First team coach Marcos Alvarez said: "Gareth is working really well. His fitness is unbelievable. He's happy with his work and we feel he will be a very important player for us next season. His fitness levels are excellent and he has that fitness naturally."