De Gea, 24, has not played for United this season as boss Louis van Gaal felt he could not focus with interest from Real Madrid, who failed to sign him on deadline-day.
He played his first competitive game of the season for Spain against Macedonia in a Euro 2016 qualifier on Tuesday.
"I felt good," said De Gea.
He added: "I really wanted to play. Now I need to keep working and see if I have some good fortune at my club as well."
Argentina international Sergio Romero has been in goal for all of United's games this season.
De Gea had been poised to join Madrid on deadline day but the move collapsed as the necessary paperwork was not submitted in time.
He has since been included in United's Champions League squad.
De Gea added: "My future will be the same as now: remain calm, keep working and improving. In concrete terms, enjoy my football. I am happy."
United host Liverpool at Old Trafford in the Premier League in their first game back following the international break, on Saturday.
Goalkeeper David De Gea says he is "happy" and hoping for "good fortune" as he looks to reclaim his number one spot at Manchester United.