The 22-year old right-back has won two Scottish Premierships with the Hoops, has been named in two Scottish Premier League Teams of the Year, has represented Wales on 12 occasions and has played in the Champions League.
Matthews admits competing in the Champions League is the peak of club football and he suggests it has been the highlight of his career to date.
"I've achieved more than I ever thought I would in football already," he told the Scotsman.
"If I'm being honest, when I was younger I never thought I would even play in the Champions League - and now I've got two campaigns under my belt.
"I will be watching it this week because it's the best club tournament in the world. Even if you're not in it, every footballer watches it. I'm looking forward to seeing who gets through, who wins it.
"When you play in it, you've got to enjoy it, embrace it, not be too nervous. You are playing against the best players, so you can only get better from the experience. We played Barcelona two seasons in a row and, in three out of the four games, we did really well.
"I do see that level of football as the very pinnacle. I think every footballer who has sampled the Champions League will tell you they want to taste it every season."
And Matthews has made it clear that Scottish champions-elect Celtic will again be focusing a lot of their energies into making it through to the knockout stages of the prestigious competition next season.
"We were disappointed with where we finished this season [in being bottom of our group] but, last season, getting to the last 16 was a massive achievement," he added.
"That has to be our goal next season, to get to the group stages and then progress."
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