Frustration and isolation are feelings Alan Shearer knows all too well from his career.
The Premier League’s all-time record goalscorer suffered three serious injuries in his playing days.
In the first of "Inside Matters", a series of exclusive interviews with football stars about the mental challenges they have faced, Shearer reveals how he understood new things about his personality when out injured.
"I learnt that I was very, very impatient, because I just wanted to get back," says Shearer. "All I knew in my life was football. For that to be taken away for four or five months was really, really tough.
"People go on about the salary that you're paid as a footballer - you should be able to cope with almost anything - but I promise you there are some really dark days when you're out injured because you're taken away from the group.
"You're with the physios every single day and there are times when you just think, 'I'm fed up with this.'"
As his goal of recovery moved ever closer, Shearer took even greater pleasure in the simple things along the way.
"With about two months to go there is a little bit of a flickering of light at the end of that tunnel," he says.
"There are different phases. One is where you can sort of walk again. Two is where you can start jogging, light jogging.
"Three is where you can sort of kick a ball again, and it's been that long that the novelty of kicking a ball again is so brilliant.
"Then it's getting back in with the group, in terms of the first-team group.
"Then it's being competitive again, and when you put all of that together it's not really until you get out on to that pitch that you think, 'Wow, I'm back in the fold of things again.' "