Raiders' Erik Harris Gives Pump-Up Speech After Epic Game, 'Keep Pushing!'

Oakland Raiders stud Erik Harris -- a former D2 walk-on who BALLED OUT on Thursday -- just gave an awesome pump-up speech to everyone who's doubting themselves, saying, "Keep pushing forward!"

Harris' story is amazing ... the dude turned himself from an undrafted free agent in 2012 into the star of "Thursday Night Football" this week -- and when we asked him about the whole journey, he said it's been pretty epic.

The 29-year-old tells us he was about to give up his dream of playing pro football a few years ago ... but he decided to spend $80 on a Canadian Football League tryout, and it changed his life.

"It was special," Harris said of his time in the CFL. "It was special. Definitely part of who I am."

Harris was able to latch on in the NFL after his time in Canada ... and for the past two years, he's been a regular in Jon Gruden's Oakland lineup.

And, finally, on 'TNF' -- he showed the country all the fruits of his labor ... intercepting the hell out of Philip Rivers THREE TIMES (one was called back because of penalty).

So, when we asked the guy to give a message to all those who are currently in the shoes he wore back in 2012 ... he delivered an epic pump-up speech about never giving up.

"Believe in yourself," Harris said. "Find that confidence within yourself and keep pushing forward because if you continue to have that focus on that vision, then things will come true."