For Andrew Cole, the biggest challenge of his life has come in the last five years.
A winner of five Premier League titles with Manchester United, Cole is ranked as the third all-time Premier League goalscorer with 187 goals, also winning the 1993/94 Golden Boot.
But, speaking on "Inside Matters", a series of interviews with stars about the mental challenges they have faced, Cole revealed how a kidney disease diagnosed in 2015 turned his life on its head.
"The past five years have possibly been the toughest five years of my life," he says. "To go down with kidney failure and try to understand how an individual being so fit for the majority of his life can go down with such a disease.
"It's a mental torture, trying to live and work with it."
"It took me a long, long time before I would even speak about it."
His life was saved when his nephew, Alexander Palmer, donated a kidney for a transplant in April 2017.
But the impact of his illness remains strong.
"There have been days that my mates, my family, have literally picked me up off the floor and said, 'Come on, we've got to get through this,' " he says.
But Cole has found that opening up about his problems has been a big benefit.
"It took me a long, long time before I would even speak about it," he says.
"The more I've spoken to my counsellor and to my mates about it, the more understanding they are of what I have and how it makes me feel. There are days I could feel a million bucks and some days I feel I can just about get out of bed.
"It's better out than in. Talk about it. If not to your mum, your dad, then to one of your mates. You've got to have someone who wants to listen, wants to help you and not give a question that at that moment you can't answer."
Part 1: Inside Matters: Shearer on dealing with recovery
Part 2: Inside Matters: Hoddle - Fighting spirit saw me through
Part 3: Inside Matters: Schmeichel - I didn't dwell on mistakes
Part 4: Inside Matters: Owen - I almost wanted to just hide inside
Part 5: Inside Matters: Fowler - Self-belief helped me through hard times
Part 6: Inside Matters: Hargreaves on pain of early retirement
Part 8: Inside Matters: Keeping perspective key for Dixon