Four walls, a bed and a slop bowl. If prison represents physical confinement and a loss of every personal freedom, what does imprisonment of the mind feel like?
"Unbearable" according to Marcus Urban, a German footballer who gave up his chosen profession -- his "first love" -- because of homophobia in the game.
In a sport infamous for macho bravado on the pitch and anti-gay chants in the terraces, Urban was battling an unspeakable shame.
A promising talent, Urban in his youth played alongside and against future German national team stars Robert Enke, Bernd Schneider and Thomas Linke.
"To play soccer basically means to rejoice in life," Urban told CNN. "I never stopped playing football. It has always been my first love and it will remain forever."
But, as is the case with so many first loves, Urban's left him with a heartbreak which was almost too much to bear.
The young midfielder, born and raised in East Germany in the 1970s and 80s in the days before reunification with West Germany in 1990, dreamed of representing his country -- but he was living an exhausting double life.
On the surface he was a rising football star, but beneath he was a man coming to terms with his homosexuality.
"I hid 24 hours a day, I adjusted," explained Urban, who was terrified of being "outed" in a sport which today has just one openly gay professional player in Europe.
"It was an almost unbearable pain, a great sacrifice, a painful price to pay to achieve my goal of becoming a professional footballer.
"Constantly hearing gay used as a curse word like s**t, made me think, 'Of course, I'm s**t.' I spent 50% of my energy trying to hide, so a maximum of 50% of my energy was available for football. It wasn't fair.
"I kept thinking, 'I cannot do this anymore, I don't want to. What is going on?' Nobody was there to help me."
Urban's love affair with football began in 1978, when he joined East German club Motor Weimar at the age of seven before moving to Rot-Weiss Erfurt in 1984.
He trained twice a day with his new team and looked capable of achieving his ambition of playing for the German national team, winning a youth championship with Rot-Weiss in 1985.
His reputation was growing and he was called up to East Germany's youth team in 1986. Urban went on to make over 100 appearances for Rot-Weiss' senior team in the German second division.
But rather than marking the start of his rise to the top of German football, Urban's spell in Erfurt proved to be the peak of a career cut short by fear, insecurity and self-loathing.
"By my early 20s I was burned out," he said.
"I realized that if I became a professional footballer, I would suffer as a man. I chose freedom over a constructed prison.
"Talent is not enough. You need the will, physical fitness, good luck and a tough mentality. But what if you hide 24 hours a day because you are gay?
"The fear and pain robbed me of my energy because I was constantly thinking of what to say, how to act so people might think I was heterosexual."
When it became clear he was in the twilight of his playing career, Urban finally summoned the courage to open up to one of his teammates following a switch to provincial club SC 1903 Weimar in 1991.
"I told only one player, in Weimar at the end of my career -- and precisely for this reason," said Urban. "He found it interesting that I was gay, I was one of his best friends on the team."
Compared to other areas of society, the football profession is statistically lacking in openly gay players.
Former United States national team player Robbie Rogers recently announced he was gay on the same day he retired from the sport, while Sweden-based Anton Hysen is currently the only openly "out" player in Europe.
Justin Fashanu's tragic story is the last time a top-flight player has been so open.