Patrick Lawson had hit rock bottom. After suffering abuse during his childhood years, and serving jail time in his adulthood, the London man thought there was no way out of the vicious cycle of violence, drugs and imprisonment that he called life.

"My whole teenage years if I wasn't on the street, I was in jail," Lawson told CBS News. "Being on the street and the position I was in, having been unhappy, nowhere to live, my mind was just focused on drugs and violence," he said. "I stopped and thought, 'Wow, how did I end up here?'"

After nearly 50 years of struggling and living in and out of homelessness, Lawson said "enough."

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"I saw the big issue and I hit rock bottom... it made me realize that if there was ever a hell, this is hell," Lawson told CBS News. Lawson was addicted to drugs and when he ended up in the hospital for an injury, he asked the doctors for help. "I believed I was going to die. I thought of my young teenage children and I thought, 'If I make it through this, I've got to turn my life around,'" he said.

Lawson received treatment for his drug addiction and was determined to get a job. He learned about a program called SHP, the Single Homeless Project, which helps homeless people in London get training for jobs.

He already had his bus driving license, so this job seemed like the obvious choice. But when it came time to actually pursue it, Lawson was apprehensive, and ashamed of his past.

"I was fearful they wouldn't take me because of my past and my record," he said. "I decided I was going to be honest... I spoke to a trainer and said, 'Listen, I have a criminal record, is that going to be a problem?'"

Lawson said the bus company, HCT Group, was willing to put their faith in him. He started learning how to drive a CT Plus bus around London. That's when he realized not only did he love being a bus driver, but others loved having him as a bus driver, too.

"First day I went out with an experienced bus driver... I got in my driver's seat and started greeting passengers," Lawson recounted.

"She said, 'Let's see how long that's going to last,'" as he greeted every single person who got on the bus.

"Then she said, 'Wow! In my 20 years of bus driving I've never seen someone so happy!'" Lawson said.

Lawson gives a friendly greeting to every person who boards his bus. CBS News

Lawson said he turned to face the passengers as they got on the bus and he shouted, "Good morning!"

"Some of them nearly fall of the bus," he joked. "Before I started, I said to myself, 'What can I do that goes the extra mile?' I looked at bus drivers and passengers and saw they weren't talking, and I decided when I get on, I'm going to greet every single passenger."

Ever since that first day of training, Lawson has done the same. "Every day, every journey, every bus stop I've stopped at for 18 months, I say 'hi' to everyone," he said.

He says it's the bus driver's job to communicate with passengers and keep them informed. And whenever there is a reason for him to make an announcement to the whole bus, he is absolutely delighted.

"I love when there's a divergence, I get an opportunity to speak on my PA system," he said. "At each stop, I say: "My name is Patrick, and I want to take this opportunity to wish you – and yes, I mean you – a very happy day."

By last summer, when he'd been driving about a year, 45 passengers had called HCT Group to compliment Lawson, according to the company's communications director, Frank Villeneuve-Smith. And because of the outpouring of admiration for the driver, he received the Hello London Award for Outstanding Customer Service at Transport for the annual London Bus Awards.

Since then, the number of happy callers has continued to rise. In October, Lawson was shortlisted for the Top London Bus Driver prize at the U.K. Bus Awards.

In just 18 months, Lawson went from unemployed to being known as the happiest bus driver in London, he said.

"I love what I do, I love driving the bus, I love being with passengers," Lawson said.

"The only thing I don't like is when I see a bus in front of me at a stop... they're going to take all my passengers," he joked. "People say, 'Patrick, an empty bus is a happy bus.' But I need people on my bus."

For Lawson, becoming a bus driver wasn't just a way to make money – it was a way to transform his life and give it purpose.

"Life is just exciting. I feel like I'm a child or a teenager. To pay bills is wonderful!" he said. "Being responsible, that's what it is... to live and work and be responsible is good."

And if people think Lawson is happy now, he believes life can only go up from here. "I actually feel myself growing. I'm growing in life."