A slim Marcus Smart and his teammates discuss his weight-loss at Media Day

We found out earlier this month that Marcus Smart lost around 20 pounds this summer and is entering preseason in great shape. On Media Day, his teammates revealed more about Smart's weight-loss and his mobility on the court.

Here's a slimmed-down Smart attending his first round of interviews at Media Day:

Jaylen Brown is frankly a little puzzled at how more explosive and agile Smart is on the court compared to a few months ago:

Al Horford, while also claiming that Smart's weight-loss appeared to be closer to 30 pounds and not 20, noted Smart's newly found athleticism during a workout they had:

Smart talked about how and why he chose to lose weight:

MassLive's Jay King learned more about Smart's dedication to shedding some pounds this summer:

Earlier this month, he said he had been "in the gym non-stop" and "eating right" throughout the offseason.

"Just making sure my body's right," Smart said. "It's a different me. It is a new me, it truly is. I'm more explosive and things like that. And I'm healthy so that's a big part for me."

An obvious concern with Smart's new frame is his ability to defend bigger players. The 6'4" guard has been able to hold his ground with all players up to the power forward position, and that is largely thanks to his bulk and strength. However, Smart wants it to be known that he still possesses the strength that he has always been known for:

All in all, Smart is looking really, really good heading into the preseason. His slim figure should be able to fill the defensive void that Avery Bradley's departure left, and don't be too surprised to see Smart throwing down some crazy dunks in 2017-18.

Follow Erik Johnson on Twitter: @erikjohnson32

Photo via Celtics Instagram page