Oscar Pistorius believes Reeva Steenkamp would not want him to receive a lengthy jail sentence.
Pistorius will be re-sentenced next month for the murder of Steenkamp, his then-girlfriend who he shot through a bathroom door in 2013.
The Olympic and Paralympic athlete maintains Steenkamp's death was a tragic accident caused by his belief she was an intruder who had broken into his apartment, an account disputed by state prosecutors.
He was convicted in 2014 of manslaughter and served 12 months of a five-year sentence, only for the conviction to be upgraded to murder following an appeal. The minimum sentence for murder in South Africa is 15 years.
In his first television interview since killing Steenkamp, Pistorius told ITV: "I don't want to go back to jail. I don't want to have to waste my life sitting there.
"If I was afforded the opportunity of redemption I would like to help the less fortunate like I had in my past.
"I would like to believe that if Reeva could look down upon me that she would want me to live that life."
The full interview with Pistorius, in which he shares his version of events relating to the night of Steenkamp's death, will be broadcast on Friday evening in the United Kingdom.
Pistorius also described the difficulties he has faced since being released from jail to live under house arrest at his uncle's home, adding: "I try and integrate myself back into society as much as I can but being infamous and famous is a difficult thing.
"Sometimes people are very caring and then other times people just act [differently]. I just quickly went to do some grocery shopping the other day and a woman came in and started screaming at the security: 'How can you allow a murderer to shop in this shop? I'm not going to support you.'
"She made such a scene that I literally just put the basket down and I walked out."