The biggest hurdle for gay athletes to come out is likely not resistance from their team or sport, but themselves. For many, self-acceptance is the hardest thing to overcome.

This is especially true at the professional level and came into stark relief with our story of Ryan O’Callaghan, the former offensive linemen with the New England Patriots and Kansas City Chiefs, who came out as gay last week. O’Callaghan said he used football as a cover from dealing with his sexual orientation, and that his inability to accept himself had him contemplating suicide after he stopped playing football.

This idea of accepting one’s sexual orientation — especially for gay men — has crystallized for me as the biggest impediment to coming out for athletes. It is such a constant theme in the myriad stories we run.

From a teenage weightlifter: “I hated myself, I realized I wasn’t going to be able to change, but I could not accept that this was going to be my life. I thought that if I could not even love myself than who would? If I could not change, I did not want to live.”

From a swimmer: “I still struggle accepting myself to this day but every day I get closer and closer to finding happiness within.”

From a world champion archer: “Before my coming out, I had a very hard time accepting my sexual orientation, and myself as a person.”

From a skier: “Instead of accepting myself for who I was, I went into denial, making up many of the excuses that I'm sure other gay men have used, like, ‘This is only a phase’ or ‘I just haven't found the right girl yet.’ "

From a track coach: “My unhappiness had little to do with location, and everything to do with not accepting myself. … As a head coach, I have walked around on egg shells, afraid of anyone knowing who I really was. I have been so fearful that being gay could disrupt my message to my team.”

From a triathlete: “Coming out was the hardest thing I have ever done, in part because I had to accept it myself at the same time.”

This struggle for self-acceptance is a mostly internal battle. The external influences are growing up in a society where the messages about being gay are overwhelmingly negative depending on one’s family, region and religion. Even people who grow up in progressive families can still struggle with accepting being different in a hetero-dominant society.

For example, O’Callaghan, standing 6-7 and weighing 300 pounds, was not bullied and said that he never heard a gay slur in his six years in the NFL. I heard the same from a young college basketball coach who just came out to his family. When I asked him what was the most difficult thing after realizing he was gay, this coach told me it was accepting himself.

Researchers have studied this issue. In an exemplary piece of reporting in the Huffington Post on gay loneliness, these two statements rang true.

John Pachankis, a stress researcher at Yale, says the real damage gets done in the five or so years between realizing your sexuality and starting to tell other people. Even relatively small stressors in this period have an outsized effect—not because they’re directly traumatic, but because we start to expect them.

“The trauma for gay men is the prolonged nature of it,” says William Elder, a sexual trauma researcher and psychologist. “If you experience one traumatic event, you have the kind of PTSD that can be resolved in four to six months of therapy. But if you experience years and years of small stressors — little things where you think, ‘Was that because of my sexuality?’ — that can be even worse.”

Accepting oneself and coming out is hard enough, but add in the layer of being an athlete and it becomes even more stressful. For a professional, major college or Olympic athlete, there is the added realization that one’s coming out is news.

It’s easy to see why staying totally or partially in the closet is the default for many. The hope is that the increasingly acceptance of LGBT people and our relationships, especially among younger people, will make it easier for people to accept themselves at an earlier age. This will make coming out easier and allow athletes the confidence to be their true selves, unafraid and no longer having to hide.