The Tigers boss conceded the after-effects of Tuesday's home loss to third-placed Watford, in which the hosts missed the opportunity to open up a seven-point gap, plagued his side throughout the first half against an out-of-form Middlesbrough.
There was little to separate the two teams until the 62nd minute when Republic of Ireland international Robbie Brady curled a free-kick low around the wall to catch out goalkeeper Jason Steele, who could only push it into the roof of the net.
It means automatic promotion remains in Hull's hands and they face the struggling trio of Wolves, Bristol City and Barnsley in their final five games.
Bruce said: "Tuesday was a huge disappointment to us all and I'm going to admit (on) Thursday and Friday they were still disappointed.
"It really took us to half-time to get going again, but we showed something, a bit of resilience and that determination to get a result. We don't want to be sitting through too many of them."
On match-winner Brady's fortunate strike, Bruce joked: "I've heard some nonsense that he watched somebody do it, whether it was (Cristiano) Ronaldo or (Gareth) Bale, and bounced it in front of the keeper. Looks to me like it hit a divot and the goalkeeper made a mess of it.
"But we needed a break and thankfully we've got it. It's put us in a really, really strong position, a good position and it's in our hands with five to play."
- Sports & Recreation