"I think retiring from international football has helped me," Reid told the Express and Star.
"With international football I would have had another four, five or six games and instead I get the chance to recover.
"I think it's helped. If I had those games in midweek and been flying back from the other side of Europe to play in the Premier League it would have been a tough ask.
"I've started 14 league games on the spin, which is more than I've done for quite a while. At the moment I'm delighted with that and the fact I'm staying fit."