Four years later, he is in the “best place ever” and wants to encourage others to reach out for help as part of a campaign with charity CALM.
Mr Lumsden, 32, had been diagnosed with depression before that night and prescribed medication.
He had been struggling to communicate with his partner and parents, wasn’t eating properly, and had been signed off work as a software developer with SSE.
One day a series of small things went wrong, and something “snapped” inside his head.
Mr Lumsden does not fully remember the events of that November evening, but knows he left his house and walked into the centre of town.
“The thing I do remember is that I was stood on a bridge in Perth, and I knew why I was there and what I was planning on doing. I knew that I was going to end my life,” he said.
“I climbed the railings of the bridge and was stood holding onto a street sign.
“I remember thinking it was really cold - I wasn’t really thinking about how it would be pretty cold in the water, just thinking it was pretty cold up there.”
But as he planned his next move, he was spotted by a man walking his dog, who called 999.
“I remember seeing a police car racing down the street adjacent to the river,” Mr Lumsden said.
“The next thing I remember is somebody asking if I was ok, which at the time I thought was a strange thing to ask somebody stood on a bridge.
“Then I remember getting dragged to the ground by the other policeman.”
The officers took him home, and he was later admitted to hospital for six weeks.
During this time he was struck by the kindness and support from local members of Andy’s Man Club, a network of support groups for men.
Mr Lumsden had been to a few sessions previously, but had not spoken to anybody.
Andy’s Man Club was the first place he went after discharge.
He credits this group with his continued survival, and he is now the lead facilitator in Perth.
“It’s been a bit of a whirlwind, but four years on from then I feel I'm in the best place I've ever been, mentally,” he said.
“I've got a house, I've got a partner, I've got a lovely stepdaughter and two dogs.
“I have such a positive outlook on life now, and it is really thanks to the continued support from that group.”
Ahead of World Mental Health Day on Sunday, Mr Lumsden urged others to talk about their feelings.
“You’re not a burden to the people you talk to, you're just telling them and they’re aware of it, it doesn't then become their problem,” he said.
“It can help you find ways to deal with the situation that you're in, and the more people you tell, the easier that's going to get, and you'll find people that have been in similar situations, like Andy’s Man Club.”
Campaign Against Living Miserably (CALM) stands united against suicide with everyone in the UK. Support workers offer practical support and advice from 5pm to midnight every day on 0800 58 58 58 or through webchat. www.thecalmzone.net.
The Samaritans are available 24 hours a day, 365 days a year. Call 116 123 for free