The forward's strike in the 2-0 Carabao Cup win was his first in nearly two years and only his second in a Watford shirt.
"It felt so great," he said. "My teammates all celebrated with me and they were so happy to get that first goal.
"That made me comfortable and relaxed and helped me through the game. I am happy to get my first 90 minutes and hopefully I can get more.
"I think physically I am better now, so I wasn't tired after 90 minutes."
Success added: "I am happy for the team, it was a good win for us.
"It will make us concentrate even more and we will be mentally ready Sunday's game."