Long swapped Hull City for Southampton last week for a widely reported £12 million transfer fee and made his debut for the club at Anfield on Sunday.
Liverpool won the clash 2-1 but the Republic of Ireland international – who came off the bench with 16 minutes remaining – missed a late chance to level proceedings when he inexplicably headed wide after Morgan Schneiderlin's fierce effort was tipped onto the bar by Simon Mignolet.
He quickly moved on from the miss, though, and is hoping to repay the faith Southampton have shown in him with regular goals.
Long told Newstalk: "I don't know whether there were any offers that were rejected before.
"But when you see them bid that much to get me, I know personally that they wanted to get me in so that gave me a bit of confidence.
"I think they realised that I was one of the starters every week for Hull, so to get me out of there was going to take an offer that makes you sit up and take notice.
"After talking with the manager and seeing the club and its facilities, it was right for me.
"When you walk into the club, you see how professional it is every day – everyone's on each other's cases and pushing each other.
"That's why we were very fit and ready to go [on Sunday]."
Long will be hoping to feature from the start when one of his former clubs, West Brom, visit Southampton on Saturday.
