Mourinho replaced Mauricio Pochettino in November but has found consistency hard to come by at Spurs.
He has won 10 of his 19 matches in charge, with sixth-placed Tottenham still four points behind his former club Chelsea in the race for the top four.
The Portuguese conceded it has not been a straightforward start to his tenure but is enjoying the challenge and looking forward to implementing his vision from the start of next season.
"Contrary to some people who want to be in the news and tell things that are not true - I am really happy at the club," Mourinho told Sky Sports.
"Difficult? Yes, but if it was not difficult it wouldn't be for me.
"I like the players and who they are. I like very much the relationship I have with them. If you see a bad face from me it is because of a bad result. I cannot change myself.
"That's just me. The reality is that I am happy and I look forward to what is coming, and even more for what is coming next season. I want to start working with them in July."