The 26-year-old was the victim of thieves who he suspects looked over his shoulder and watched him enter a four-digit code on a padlock which he used to secure his locker at the 24-hour Pure Gym in Bath Street.
In total, he has lost around £1600 worth of personal items including a £650 mobile phone, a £300 watch, a £400 wedding ring and £270 in cash that the thieves took from his bank account using his bank card.
As he tried to work out how they could know his bank card pin number, he realised he used the same four-digit number for his gym locker.
The Motherwell man, who asked not to be named, said: "I am annoyed with myself for using the same number as my bank card, but I'm sure it's something that a lot of folk would do.
"I certainly won't be making that mistake again."
He went to the gym at 11pm on Thursday after he finished a shift at work.
When he was putting his items in the locker, there was a group of men in the gym who, looking back, he realises did not appear to be using any of the equipment and were just "hanging about."
According to his bank, the Royal Bank of Scotland, his card was used at an ATM on Sauchiehall Street at around 11.10pm and £270 withdrawn from his account.
He added: "They obviously moved very fast to open the locker and get out of the gym.
"When I went back to my locker at around midnight, it looked from the outside just as I had left it.
"It was locked, but when I went through my clothes I realised my wallet, phone and watch were gone.
"And my wedding ring was in a small compartment in the wallet. It's my wedding ring that I'm most gutted about losing.
"I only got married in summer last year and you obviously can't put a price on your wedding ring."
Police Scotland confirmed the theft had been reported and they are investigating.
Charlene Robb is the manager of Pure Gym's Bath Street branch.
She said: "I'm sorry to hear this has happened and we will be helping police in every way we can.
"We have CCTV of the main gym area. We have passed that footage to the police and hope the culprits are caught as we don't want them in our facility.
"I would advise gym users to be vigilant when putting in their code on their padlocks and also advise against using the same number as your bank card pin number."