He then went on to do a fine arts degree and he continues to draw, paint, sculpt and practise photography. "It's very difficult to shut something like mental illness out. I tried doing that for years and I got nowhere," he says.
"But as soon as I started understanding what was going on, how it was working, I was able to apply what was going on within me to a more beneficial end."
Hamill notes that there are many elements to recovery from schizophrenia, including family, friends, medication, psychiatrists, psychologists and support centres like Dublin's Basin Club, where he is an active member.
Alongside these, he believes that the creative process is an essential tool, but that it doesn't have to be high art.
"It could be you doodling when you are on the phone, it could be you trying to write your name in an interesting way, anything," he says.
The process of art has a recognised therapeutic value, according to Bríd MacConville, an occupational therapist in mental health services with the Health Service Executive (HSE).
She is also a practising artist, and three years ago she set up an arts initiative within the mental health services in the northwest.
The programme invites professional artists to run workshops for people with mental health conditions in nine centres around counties Sligo and Leitrim.
The artists guide participants through activities such as drawing, painting, claywork, photography and sculpting.
"People choose to come and the focus is on the art, not on the condition," says MacConville, who has been developing the initiative in a "quiet and small-scale way".
Supported by the HSE, the programme has also linked in with community-based groups and with Sligo County Council Arts Office for individual projects.
"It's not a quick fix or a cure-all. It's about creating an atmosphere and an environment where people could be respected for who they are," she says.
The approach can also help to combat social isolation. One of the most rewarding outcomes for MacConville involved a woman with schizophrenia who had been institutionalised for much of her life.
She took part in a photography workshop, and then her occupational therapists brought her into town so she could choose an outfit to wear for the exhibition at which her photos were to be shown.