Donald, a former Protea fast bowler, said he would have refused the offer had someone else was in place of Kirsten, who recently guided India to World Cup triumph.
Donald said the feeling on being offered the job was the same when he was told to play for South Africa after the country was readmitted to international cricket in 1991.
"It was the happiest moment of my life when Gary called me (about ten days earlier)," Donald said.
"It has always been my dream to work with my own people. It felt like the call I got in 1991 from Dr Ali Bacher (then chairman of the United Cricket Board of South Africa) to say that I would be playing against India.
"I would probably not have agreed if someone else was in charge. We are old friends. We played together for a long time. (Kirsten) treats people like people," Donald said.
Cricket South Africa on Monday announced that Kirsten will be the head coach of the national team and Donald would be the bowling coach.
Donald admitted that he had upset both the New Zealand cricket boss Justin Vaughn and a prospective tenant for his home in South Africa.
"My bags were already packed (to go to New Zealand as bowling coach) when I got the call from Gary (Kirsten). It took me all but half a second to say 'yes'," Donald said.
He was happy to remain at home now although he had already struck a deal with someone to rent his house while he was away in New Zealand.
"I can now happily kick him out even before he moves in," Donald jested.
The ace fast bowler said Vaughan had initially been very angry with him for reneging on his deal with New Zealand but understood the situation when Donald explained that he would be most happy to work with the Proteas.
