With that goal in mind, he passed his driving test and began a course in film and TV media at Edinburgh College.
Initially, he drove back and forth from Elvanfoot to Portobello but he made a fateful decision to take up residence in the halls.
Just six weeks later, the promising student, who was aged just 18, was found dead in a bathroom there.
His parents Colin and Mandy were woken by police officers in the early hours of November 26, 2017 – to receive the devastating news that would change their world forever.
While no-one has ever been prosecuted for the teenager’s death, it is believed the juice he’d been drinking that night was spiked.
Colin said: “Greg was completely anti-drugs and was planning to make a film about it for his course.
"So when we were told he’d died from a suspected drugs overdose we said no way, not our son.
"Experimentation was ruled out in any case as he had the equivalent of five Ecstasy tablets in his system.”
Police Scotland have worked closely with Colin and Mandy and in 2018 fully supported their decision to launch Spike Aware UK – a charity which raises awareness of the dangers.
They have since produced 20,000 flyers, 15,000 protective bottle lids, and 10,000 beer mats for distribution around universities, colleges, nightclubs and pubs.
Now, they are fronting spike awareness presentations for S6 pupils and first year college students, which launched recently at Greg’s old school Biggar High.
And they are taking their campaign to the top.
Colin said: “We’re looking to make the offence of drink spiking more serious and have had meetings with Police Scotland and the Scottish Government.
"We want it to be treated like drink driving. It’s not just a prank – it costs lives.”
Sadly, Police Scotland has not been able to secure enough evidence for a conviction in Greg’s case.
The talented youngster had already made an appearance on the big screen, in the movie Outlaw King, and was booked for Outlander – sadly, he was gone before that.
However, Colin and Mandy are determined to ensure their son’s name lives on; in 2018 they launched the Greg Mackie Speedway Academy and have raised £15,000 to realise their dream of opening a motor sports facility to help disadvantaged children.
Greg was also a talented speedway rider; he won the British Youth Championships and was a member of the Castleford Castles team.
Colin added: “We’d love to set up the facility in Clydesdale; we need land though.
"We already have bikes and professional riders ready to teach but finding somewhere to set up has been a problem. If anyone could help, we’d be delighted to hear from them.”
Colin, who is a courier, and Mandy, who runs a gift shop, are still raising funds. If you can help, email [email protected]
To find out more, visit m.facebook.com/groups/234465676746306.
And for Spike Aware UK, visit www.facebook.com/groups/2198515327068094/?ref=share.