The 27-year-old Red Devils forward managed a disappointing 12 goals in 27 top-flight appearances as Rooney’s season was hampered by both form and injury woes.
The United striker, who was linked with a move to Chelsea in the summer, has made a bright start to the current campaign, netting three goals in six appearances.
And Rooney feels in good shape after a demanding pre-season campaign.
“I know myself that last year probably wasn’t my best season,” Rooney said.
“But there were times when I was playing in different positions and I felt I didn’t really get that consistent run of games up front.
“Sometimes, when you’re not playing that position all the time, it’s difficult to adapt. I think I wanted to prove to myself really rather than to anyone else, in trying to come back fit and sharp and scoring goals.
“I feel good, I’ve scored a few goals and I’m playing every week so I’m enjoying it.
“Honestly, the training has been so hard, we’ve done a lot of different types of training, a lot more running -long running, quicker running, sharper running.
“I feel that’s been of benefit to me. I feel as fit as I have done. I’ve had a couple of injuries in pre-season but I feel great. I’m in good shape, just wanting to play and train every day.”
MORE: Man United latest news
MORE: Arsenal latest news
MORE: Chelsea latest news
MORE: Liverpool latest news