(CNN)David Norman is proving that if you keep chasing your dreams you will succeed.
The Harlem native, who served multiple prison sentences and battled an addiction to heroin, graduated from Columbia University School of General Studies last week. At 67, Norman is the oldest graduate of his class of 547 to receive his bachelor's degree. The average age of the graduation class this year was 29.
"Columbia University School of General Studies is dedicated to serving nontraditional students who want to pursue a traditional Ivy League education," said Christina Gray, communications officer at Columbia University. "And David Norman is but one example of the kind of exceptional students we serve."
Norman's journey to the graduation stage wasn't an easy one. When he was a teenager, he fell into a life of crime and into the grips of drug addiction.
"I was a very shy kid, and I was also selling narcotics, and in that capacity you were taught not to show feelings," said Norman in a press release."One of the things I realized early was that when I got high, I was able to function socially, which was one of my biggest problems."
Norman's last prison stint ended in 1995; he was serving time for manslaughter. After he was released, he took a job volunteering as a counselor for a transitional services program. This program helps freed inmates transition back into society.
About two-thirds of released prisoners are arrested for a new crime within three years, and three-quarters are arrested within five years, according in the Bureau of Justice Statistics.
"That job changed my perspective. It let me know that I have something to offer," Norman said. "I decided I would devote my time to working toward something bigger than myself."
Norman said he has maintained a drug-free life for over 20 years. On May 16, he received his bachelor's degree in philosophy.
"I remember a time when people would avoid me on the street, because of my attitude," said Norman. "Now I smile and say hello to people and ask them how they're doing."
He works as a research assistant at the Columbia University Mailman School of Public Health. He also continues to mentor those who have been incarcerated.
"When my perspective changed, my life changed. Whatever happens outside has to begin inside."