After going eight games without a goal for the Red Devils, Lukaku was dropped to the bench for Sundays Premier League clash against Everton.
Speaking before the game, Mourinho said Lukaku was short not only of goals, but also confidence.
With Manchester United 2-0 up – thanks to goals from Paul Pogba and Anthony Martial – Lukaku came off the bench for the final 25 minutes.
Mourinho was pleased with the Belgians cameo and said he is confident life will change for Lukaku once he finds the back of the net again.
I think when he scores one goal, life will change for him, Mourinho told MUTV.
At the moment, I think hes under that pressure that normally the strikers put on themselves, plus the press obviously. So its not an easy life for strikers when they dont score goals.
I think hes feeling a little bit of that, but he came into the game with good movement.
Romelu showed good attitude, he wasnt losing the ball, his first touch was better, he was much more composed, so he will be better.
I have no doubts that soon he will start scoring goals.
Martial enjoyed one of his best performances of the season for Manchester United, with his curling effort in the second half putting the home side 2-0 up.
Chris Smalling brought down Everton forward Richarlison and Gylfi Sigurdsson converted the penalty with 12 minutes remaining but United held on to a vital win.
On Martials performance, Mourinho added: He coped well with his development process.
He took quite a long time to understand what we want from him, quite a long time for his brain and body to be ready for how we want him to play.
At the moment he is solid, playing very well. Even if he doesnt score, to create what he is creating, it is a solid performance for the team. That is what we need.