Quarantine is starting to get to Serena Williams.

The tennis icon, who has been holed up in her Palm Beach Gardens home, has been documenting her attempts to pass the time these past few weeks, and according to her latest Instagram post, it seems like she's had to resort to...hitting a tennis ball against the wall, over and over again.

The activity was, in fact, a challenge from her friend Roger Federer, who encouraged his athlete pals to see how long they could bounce a tennis ball off of a racket without dropping it. Serena didn't hesitate to accept.
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“When Roger challenged all of us, I knew I couldn’t let anyone down, I knew I had to do this,” Williams says in the video, which she captioned, "4 days later." 

“I’m on day three, or four, or five … I don’t know. All I know is that I’m still doing this challenge!” she adds. “I’m hungry, I’m tired, I’m thirsty, but I won’t give up."

Watch below: