The ex-Luton Town midfielder endured a harsh baptism at Oakwell last season, with the 23-year-old failing to justify the expensive six-figure outlay to secure his services last summer.
After signing for the Reds while he was still recuperating from a broken leg at Luton, McGeehan was loaned out to Scunthorpe United in January to boost his game-time levels, with the 2017-18 season representing a toughening-up process.
Ready to make his mark after playing catch-up on the fitness front, he said: “After a long injury and you are on the sidelines a lot, you have to be tough.
“I came to Barnsley and jumped up two leagues and thought I did well. But looking back now, I think: ‘was I fully fit?’ At the time, you think you are, but now I know I am back to myself, mentally and physically.
“Hopefully, I can now show the fans what I am about.
“It was a big investment and they signed me when I had that injury and it is up to me to repay that fee.
“It was a big year in terms of everything and with all the things at the time, it was tough. I had three managers and played for two different clubs in two different leagues.
“Now it is lovely to come back as you forget how big a club Barnsley is with the stadium and facilities. There’s even a new £80,000 gym.
“With the new owners and management, it’s really fresh and you get that feeling. It bodes well.
“With our manager now, it is about understanding that work off the ball is just as important as on the ball with the counter-pressing.
“The first few weeks were just about pressing and really hard in intensity and all the lads enjoyed it.”