Stack spent the last couple of years with National League side Eastleigh, but he retired from playing in September to join the Hornets’ backroom staff.
In a recent interview with Betway, the 37-year-old admitted that he felt the time was right to call time on his playing career.
“I was out of contract in the summer and wondering how long am I going to be able to keep churning out one season after another,” he said.
“And then, before you know it, you maybe get a little niggle and miss a few months.
“You’re not as desirable once you get to 37, 38. The salaries start to come down.
“I don’t want to end up scratching around for a club and not being paid over the summer, as has happened before. It’s a real nightmare.
“I’ll miss it, big time, but I think there comes a time where you’ve just got to do what’s right. There’s more stability now for the family. I thought it was the right time to make that move over to the other side.”
Prior to his stint at Eastleigh, Stack enjoyed a brief spell in 2016 as player/coach with Kerala Blasters in the Indian Super League.
The move reunited the goalie with ex-Reading boss Steve Coppell, who had taken charge of the club in June of that year.
Having finished bottom of the table the previous year, Coppell guided Kerala to second in the standings, just one point behind Mumbai City.
They successfully came through a penalty shoot-out to see off Delhi Dynamos in the play-off semi-finals to set up a final showdown against Atletico de Kolkata.
The Blasters took the lead before being pegged back just before half-time. Neither side could find a winner and the game eventually went to penalties.
Stack saved the first one, but Kolkata scored their next four to secure the title. Despite the defeat, Stack says his Indian adventure was one of his best experiences in football.
“It would have been a fairy tale (to win),” he added. “But it was about more than winning the trophy. It was about everything that came with it.
“It wasn’t until you started putting a few things down on paper on the plane on the way home that you think: ‘Blimey, what an experience’.
“What I experienced off the pitch with that group of players will always mean more to me than what happened on it.
“It surpassed all my expectations.”