Shrewsbury manager Steve Cotterill feels he came back to work too soon last season following Covid-19 and pneumonia, which saw him have two spells in hospital.
The 56-year-old spent time in intensive care after initially testing positive for coronavirus on January 1.
Cotterill was discharged from Bristol Royal Infirmary in mid-February, only to then be readmitted on March 1 for Covid-19 pneumonia.
The Shrews boss missed 24 games since the end of December, but was back in the dugout for the final three matches of the Sky Bet League One campaign.
After returning to New Meadow for the start of pre-season, Cotterill gave an emotional interview to Shrewsbury's club media in which he thanked everyone for their "overwhelming" support and also revealed the extent of his own personal struggles to get fit for work.
"I sort of feel I let you down last year, the chairman, board of directors and staff, players and supporters really," Cotterill said.
"I wanted to get back before the end of the season, and managed to for the last three games.
"I am not sure that was a good idea really. I think I was not anywhere near ready. My recovery time after watching a game was quite lengthy.
"Since the season finished, I have been in the gym every week trying to get myself fit to come back on July 1, just to be around and back with the players."
Cotterill has spent over 25 years as a manager, taking charge at the likes of Birmingham, Burnley, Bristol City, Nottingham Forest and Stoke.
The 56-year-old fought back tears as he reflected on the support received during his recovery.
"The love and kindness that has been shown to me over this tough period is overwhelming really, so I just want to thank everybody for that," he said.
Shrewsbury open their 2021/22 campaign at home against Burton on August 7.
