Delve, capped eight times, said: "It's always been a big motivation through all the injuries and absences to get that start for Wales. It has been so frustrating.
"What got me though all the miles I've run on treadmills and rehab sessions was putting myself in a position to start for my country. All I can do is take any opportunity thrown my way to prove myself to the coach. I know I've got it in myself to produce.
"It's been a frustration to be out of the Wales team and I'm desperate to get on the field. It's been a pretty good year with Gloucester and Wales considering I've come back from damaging my cruciate knee ligaments.
"It was fantastic to be a part of the Grand Slam success. But we can't rest on our laurels and part of the reason behind this tour was to push the boundaries. We failed first time, now we have to look at the second chance."
Wales were heavily defeated by the Springboks and came off second best at the breakdown. But Delve believes the pack can match their South African counterparts.
Delve said: "The Boks are among the most physical teams around, up there with New Zealand and England for sheer size.
"But we've got big guys as well and we have to get away from this thought that they have a right to run over us just because their Springboks or Kiwis. It's just 15 men against 15 and we need to show we can match them.
"You need to win the arm-wrestle against South Africa, otherwise you can't release your flyers like Shane Williams and Mark Jones who showed they are up there with the best."