The powerful forward scored one goal and set up another to help Villa book their place in the fourth round of the Carling Cup with a 3-1 win on Wednesday night.
Heskey told the club's official website: "You come into a game and you're looking to make an impact - it was nice to have that impact.
"The lads were plugging away and doing well. When you come on as a sub you try to do something positive and that's what I managed, which was great.
"It was nice to get out there and contribute to the team. The manager told us it's not just the XI on the park, it's the subs too and the lads in the stands as well.
"Everyone is part of it and we need everyone focusing on the same goal. That's what we're doing.
"For my goal, when you get time like that, it's a bit more difficult - it's the ones where you have a split-second to think about it that you seem to do better with. But I managed to get it out of my feet nice and early and drill it home.
"The lads at that point were creating a few chances. The goal gave us that little bit of a boost."