Originally from the Rahoon Road in Galway city, Jim now lives in France and was taken aback when he was asked to take part.
But he said that taking part in the programme helped him with his own "breakthrough".
"I don't watch too much TV so when they said the title of the programme, I said, 'no thanks'," Jim told the Herald.
"Then I agreed to meet the guys and I asked them to find a part of Ireland where there was a charity that suits the kind of thing I was interested in, a charity on the fringe, under the covers, without much acknowledgement about what they do.
"The real breakthrough for me came midway through. I am 42 years old and I have just been able to accept the fact that I battle with depression. I have not been able to say those words out loud before.
"I asked them if there was something that could be done, put in place that would help people in a similar situation, in the general area of mental illness."
Jim, who is a multi-millionaire as CEO of international IT learning company Pulse Learning, was invited to live alone on the minimum wage as an IT worker in Finglas. He encountered experiences of unemployment, substance abuse, serious physical illness, depression and suicide.
But he was on a mission to try to find people who were genuinely trying to improve the lives of others.
"I didn't know if we would find a project so suitable," Jim said.
"I was very fortunate. I wanted something sustainable, not something that you could hand over a cheque and that would be it."
Jim said that he was stunned at his own reaction and those of the people he was able to help, with tens of thousands of euro of his own money.
He said Irish people were very private about their own social engagement but he realised that his very public donation would encourage others to donate.
"People do a lot of private donations. Irish people are very private," he said.
The new series of The Secret Millionaire airs tonight at 9.35pm on RTE One.