I was a lonely child – but before you get your hankies out, I should explain that this was almost completely by choice. At lunchtime at my first primary school, I used to walk around by myself because I thought playing Mummies and Daddies was so passé. I preferred to make up stories about werewolves and secret castles. I still think of myself sometimes as a tubby seven-year-old, plodding about with my head in the clouds.

Then, one day, I got over the love of my own company and began to make friends. First one, then two, then lots, whom I love very much. I hope we all end up in the same old folks’ home, complaining that the music isn’t what it used to be and that our grandkids never send us a hologram on our birthday. Friends are great, because you can eat lunch with them and go with them to the disco. Plus, they will almost always tell you if you have food on your face. I like their attitude.

However, for this next bit, I’m going to have to leave my facetiousness behind, because my friends have been incredible and continue to be incredible every single day of my bizarre and inconsistent existence. To watch someone you love disappear behind a cloud of mental illness is harrowing. To know that you can only do so much to help them is perhaps even worse.

I don’t think there’s a perfect way to be friends with someone who is mentally ill, anymore than I believe there is a perfect way to ‘treat’ mental illness in general. Every person is different and I’d be lying if I said that I have been a failproof friend to everyone in need of my help – mainly because I’m very human, but also because I’m a bit of a wet fish. But I have learnt some things, so bear with me here.

One of the hardest things to realise when your friend becomes ill is that they may not take to your brand of treatment. You can’t make them wake up every morning and say 10 nice things about themselves while looking in a mirror and listening to Christina Aguilera’s ‘Beautiful’. You can ask if they’ve tried anti-depressants, but if they’d rather treat themselves with St John’s wort and daily jogs you should let them. On the other hand, if your friend is refusing to get treatment and is putting their life at risk through their behaviour, you should tell someone who can help them; a charity like Mind or Student Minds often provide links and contact details. You can strike a balance between being involved in their welfare and allowing them the freedom to treat their illness however they please.

You can show your support in multiple ways. Shortly after my dad died and I entered into a long bout of depression, my friends bought me friendship bracelets and assured me this meant I could depend on them. In Year 13, one of my close friends became very ill. I took a bus across town and went with her to the GP – she didn’t want to involve her parents, but she didn’t want to be alone. Before the appointment we ran through exactly what we were going to say and, afterwards, we went to the corner shop to buy chocolate.

During Easter term last year, I had one friend I was very dependent on. We would sit and watch YouTube videos together, because I didn’t want to leave my room. We didn’t need to do anything more extreme than that because it was just nice to know I wasn’t alone. Even when he left, it didn’t matter that I was left by myself, because I had the assurance that somebody cared. And sometimes your friend will have to be alone – on a long train journey, during a long sleepless night, on their way to a counselling appointment. If you remind them, in small ways, that you’re on their side, they’ll be able to focus on getting better.

My penultimate word of advice might sound very negative, but know this – illness can change that person you love into someone you can’t stand, someone who brings you more pain than happiness. Don’t be afraid to be honest with them, and with yourself, if this happens. Most illnesses don’t last forever and, sometimes, anxiety and depression can warp your perception so that you don’t realise that you’re behaving like a complete twat – trust me, I’ve been there.

Finally, know that you’re surprisingly loved. A few nights ago I went out for a drink with a friend. He told me that becoming my friend was the highlight of his second year. I was gobsmacked of course, because last year I was depressed and about as interesting as a cheddar cheese sandwich. But he loved me anyway.

I guess the lonely tubby kid is doing okay.