The Birmingham-born defender, who is set to retain his place for Tuesday's trip to Hull, said: "Everyone trains hard so that when you are called upon you are ready.
"It's more about the mental side as well, and I see myself as a seasoned pro now - I am better able to look after myself because you never know what will happen.
"The manager didn't say anything to me before the game. But looking around the dressing room, I was the only fit centre-half.
"I just had to make sure I got my head right."
Knight added: "It has been very frustrating but I have never had a reason to knock on the gaffer's door because the team has been doing so well.
"If I had knocked on it I would have probably had it slapped back in my face!
"The team has done tremendously and it has been nice for me to come in and fill Martin's (O'Neill) place and keep our run going.
"He is going to be missing for the next few games, and hopefully I can come in and do a good job."
Villa had found themselves 2-0 down at home to the north Londoners after dominating the first half and spurning several chances.
"The manager said to me afterwards: 'That was a great strike!' Knight said. "It was nice to get the goal but the whole team worked for it. I don't want to take all the glory.
"We came back from 2-0 down against Arsenal and that just shows the fighting spirit we have.
"It has been a long road this season. It was great to keep our run alive and to get a goal like that against Arsenal feels tremendous.
"It was in front of the Holte End too - I will never forget it, I don't know when my bubble will burst!"