In a revealing interview on BBC Radio 5 Live, the 30-year-old swimmer opened up about his troubles away from the pool that led him to consider taking his own life.
Thorpe made an unsuccessful attempt to qualify for the London Olympics after coming out of a four-year retirement in late 2010, and instead became a favourite among UK viewers, working as a TV pundit this summer.
Now he has confirmed he is looking to add to his Commonwealth titles in Glasgow in 2014 and still harbours ambitions to compete at Rio in 2016.
"I'm going to work in two-year cycles. I'm looking to swim until the Commonwealth Games and then make a call on whether to swim through until the Olympics after that," he said.
"Starting out when I came back I knew the odds were stacked against me (to qualify for the Olympics). I thought it was 50-50. Realistically I thought it would take three years to get back."
Amongst his revelations Thorpe said he had been treated for depression since he was a teenager and that it had led him to drink during the night in the lead-up to the 2004 Athens Olympics.
He also recounted that he had been too "embarrassed" to tell even his family about the disease until this year.
While Thorpe believes he has now learned to control the problem enough to speak about it publicly - he has also released an autobiography entitled 'This Is Me' - he admitted there were "still times that are really tough for me".
"I realised that I had depression early. I was having treatment for depression when I was a teenager," he said.
"Depression comes in bouts. You can feel okay most days and then just get hit with it. I experienced that through what was mostly a very successful swimming career.
"I have struggled with it before but I feel like I am on the other side of it. There are still times that are really tough for me, but I feel as though I know enough about it."
Asked whether he had ever contemplated suicide during a glittering career that also saw him claim 11 world titles, he added: "Yeah, I wouldn't talk about it otherwise. It's not something that is a throw-away line.
"When you go through what the process of what it would be like and it becomes and obsession in your mind where all rational thought is devoid in that situation you realise that this has gone beyond just a thought.
"When you are trying to get it out of your mind rationally and you can't. To consider it as being a rational solution to the way you are feeling you realise this is a problem, that this isn't just a fleeting thought or feeling.
"This is a very clear guideline that you do need more help and that you're not in control of your life and that the irrational thought has taken over."