Phil Mickelson is usually pretty funny when he posts videos to social media, including his “Phireside with Phil” series. But on Sunday, Lefty took a more serious approach.

The five-time major champion took to social media to reveal that he’s lost 15 pounds in 10 days in order to “reset” his body ahead of the 2019 Open Championship at Royal Portrush in Northern Ireland this week.

“Let’s get real for a few minutes,” Mickelson said to open up the video. “I haven’t posted anything because I haven’t been feeling good about himself and the way I’ve been playing, and so I haven’t wanted to do anything or be in public. The last 10 days I’ve done what I call a ‘hard reset’ to change and try to make things better.”

The 2013 Open Champion said that he lost the 15 pounds by completing a “six-day fast with water and a special coffee blend for wellness” and going on a retreat.

“I don’t know if it’s going to help me play better or not, but I’m willing to do whatever it takes to try to get my best back,” Mickelson said.

Watch the full video below.