The 25-year-old, who has made just five starts for United this season, scored in United's 4-0 victory at Newcastle United on Saturday.
"I'm happy, I played for 90 minutes and it's a long time since I started a game," Hernandez told MUTV.
"The World Cup is coming so I need time to prove, whether they give me one minute or 90, that I'm ready and that I want to contribute to the team to help us have a better season.
"It's been a very hard season for me, but I'm trying to be very patient, and to work to try to speak on the pitch. I have nine goals at the moment, so I'll keep working, be patient and speak on the pitch like I always do."
Hernandez joined United from Guadalajara in 2010.