The 86 year old has been forced to cut down on physical activities because of the illness, which affects the lower limbs, but Bush is adamant he's not letting the condition get him down.

He tells U.S. talk show host Larry King, ""I've got a leg, you probably may have noticed how I limped in here. But it's something called Parkinsonitis. It's like Parkinson's (disease) in the lower extremities. So you lose your balance. Nobody wants you on their team anymore.""

And the former president still hopes he will be able to fulfil his dream of completing a parachute jump on his 90th birthday in 2014.

He adds, ""(I want to do) one more (jump), (on) my 90th birthday, June 12th, 2014... It's all set.""