The 20-year-old Belgian attacking midfielder was handed a rare start by Louis van Gaal on Friday night and it paid off as he scored the only goal in a 1-0 win at Aston Villa.
After playing just seven times from kick-off in the Premier League last term, Januzaj is now looking to grasp his opportunity under the Dutchman with more assured performances for the Red Devils.
"I'm ready to get back to my best and do everything that I can do," Januzaj said.
"Of course [I'm improving], the manager has spoken to me a few times and I felt that I haven't been myself but I hadn't had many games, so hopefully I can play more this year.
"I've not played for a long time, so I was happy to score my first goal of the season.
"I'm happy to play and give everything for the manager and the club. I'm happy at United and I'm happy with the way the manager has worked with me."