The song is a ballad about self-doubt, guilt, depression and suicide, and Lamar said he picked the fan out because he was "singing his heart out".
"I can see Logan pouring his ... heart out, because he going through real s***, just like I go through. No matter how much money, no matter how much fame, we still hurt," Lamar said.
Kendrick Lamar says people like Logan inspired him to write To Pimp a Butterfly. Photo / Supplied
He went to the four-day festival to see Lamar and spent a whole day waiting at the front of the stage Lamar would perform on that night.
GetGowenz said he and his brother were bullied in school but his brother "hid his true emotions because he felt like admitting he was depressed was giving up".
Two days before the concert, Logan had submitted a 1000 word essay for his English class about the very song he was singing when Lamar spotted him.
"He allowed my brother to dance with him on stage while 30,000 people watched and cheered him on. He got to watch the rest of the concert from the side of the stage and walk with his idol to his car before he left," writes GetGowenz.
"My brother can say what he wants but I know the true pain and stuff he's [gone] through. Since the concert ... he is serious about losing his weight. He found a great girlfriend. He's taking school seriously. This has 100 per cent been for the best of my brother and I'm so thankful he got the chance to join his idol on stage."
You can watch the video of Logan being pulled up on stage below.
