Mata has won a string of honours with club and country, as well as twice being named Chelsea's player of the year, but has lost his place as the club's designated No 10 to Oscar this term.
Mourinho warned the Spain international to adapt or risk being more permanently cast aside but Mata has vowed to rise to the challenge - and reckons he can have his best season yet at Stamford Bridge.
"I just keep going, train well and prepare for every game," he told Chelsea's official website.
"I just have to do my best in training and in games. It's important to play with the ball and without the ball, but I'm very happy and looking forward to playing a lot of games throughout the season.
"I try to improve every season; my first and second seasons were fantastic but I want this one to be even better so I will try to improve, score goals, assist and do what I have to do.
"I'm not the kind of man that gets down. I always believe in myself and train really hard. This is my way to behave, to be positive as much as I can.
"I have really enjoyed playing for this club in the last two seasons. I know what I can give to the team and I'm just trying to do that.
"I have to do this (to adapt to Mourinho's instructions). I try to do my best in every game and I think I'm doing that."
Mata was an influential starter in Chelsea's 4-0 Champions League win at Steaua Bucharest on Tuesday night and the 25-year-old has urged his team-mate to end the group stage on top.
"We have two games in a row against Schalke and we will try to win all six points," he added.
"It's going to be difficult. They are top of the group right now, but if we do it we will be in a good position to qualify.
"We have qualification in our hands. We needed to make up for the last game and we did that. Now the story continues and we have to keep winning game after game and finish top."