Bruce guided the Tigers back to the Premier League on Saturday after a two-year absence from the top flight.
However, the former Black Cats boss revealed that it was tough to build himself back up after being discarded by the club.
He told reporters: "I took over a team that had avoided relegation on the last day. We finished 13th in the first year, 10th in the second, balanced the books and then I got the sack after 11 games.
"Of course it hurt me. I thought I'd get a chance and it didn't happen. But then you dust yourself down because you have to work hard for the chance to work at a club like Sunderland, and it's taken away from you.
"So you have to rebuild yourself and it's tough. Then you have to get ready for a challenge again."
Hull earned promotion on the final day of the Championship season by earning a point in their 2-2 draw with Cardiff City.