The 26-year-old won World Championship gold in Daegu in 2011 and was selected to captain the GB athletics team in London.
However a knee injury which required an operation last December hampered the Welshman's 2012 season, and he eventually had to settle for fourth in London, as 2004 champion Felix Sanchez claimed a second Olympic title.
Now back to full health, Greene is expected to lead the British charge at this year's World Championships in Moscow as he looks to emulate Sanchez, Edwin Moses and Kerron Clement in winning back-to-back world titles.
He said: "The only reason I can talk about the Olympics now is because I've done a few months of exceptional training and I'm in a good place.
"Do you know how many weeks of training I'd done this time last year? Zero. I'd had an operation in December on my knee and was just trying to do walking exercises.
"I'm going to South Africa for a few weeks of warm-weather training soon, just as I did last year.
"I remember doing a lap in 2min 40sec and having this huge smile on my face because I'd been able to run without pain.
"I thought 'I'm going to be OK', and the hope still burned for London. In fact, it did until the competition itself.
"In London I was months short and with perspective I can now give myself a pat on the back and understand that fourth was the best we could have got out of the situation. It's just for the few months afterwards you don't see it like that."