She wears the number 40 shirt. A number with no obvious importance in football, but for Charlton Athletic goalkeeper Katie Startup, it holds a special significance.

According to the World Health Organization, one person dies every 40 seconds to suicide. Extrapolate that across a 90-minute match, with a 15 minute break for half-time, and the number of people who take their own lives is 157.

"My first reaction was really just shock," says Startup. "You hear that and it really struck a chord with me, it puts everything into perspective."

For Startup, mental health struggles are something that those closest to her have been through and she also knows people who work to help mental illnesses. When she decided to raise awareness for a cause at the start of the season, it was an obvious choice to focus on mental health.

She said: "I knew mental health was something I wanted to make an impact in, it was the one I wanted to really push and raise awareness for.

"Since goalkeepers so traditionally wear number one, I knew that by changing to such an out of the blue number like 40, people would ask me why. By asking that question, that is starting the conversation."

Playing sport at a high level can be mentally tough, especially if you make a mistake that costs your team a result. Startup's position as goalkeeper only heightens that sense of mental pressure. But she knows exactly what to do after an error.

Startup said: "My mindset if I’ve made a mistake or let a goal in is to be the first person to speak on the pitch. Obviously goalkeepers can be very vocal anyway but I find that if I’m very vocal, then instantly I am focussed back on the game and I’m not dwelling on the mistake.

"Being vocal is about not letting other people see that it is playing on your mind. If I was vocal and confident before a mistake and am vocal and confident after, that gives my team a bit of a boost and they have more belief in me.

"I also think being in a team is very useful. You sometimes see it on the pitch. If someone makes a mistake, we get around them and get them back on track. I think in football, we are lucky that we are surrounded by those people who know you and can support you, rather than having to recover on your own like they do in an individual sport such as tennis."

Over the past few years, footballers speaking out about mental health has become more commonplace and players like Startup are taking a stand to shed light on issues that mean a lot to them. But Startup still thinks more can be done when it comes to integrating mental health support into football.

"I think maybe a little more support within clubs would be good," she said. "We are quite lucky that at Charlton we have a lot of support with psychologists, who do such a great job. To have someone there for the players to go and talk to while being confidential, without going back to the manager, is so crucial.

"The more we speak out about it, hopefully the more we realise that this is something we need to work on and address within a sporting environment."

However, it is not just within a sporting context that Startup wants people to speak up about mental health issues, she wants everyone to do the same. Rather than keeping things to oneself, Startup hopes people will have the courage to speak up.

"I do believe that talking about it [mental health] is such a big relief, whether it is with a close friend or a family member. I know it can sometimes be quite hard to talk to a family member because there are thoughts of being a burden or worrying them. But thoughts like this, which self-sabotage, do not help and you should try and talk to people about it."

Startup was speaking to NewsChain ahead of today's World Mental Health Day. This year's theme is suicide prevention. More information can be found on the World Health Organization's website.