It's been about a month since Sean Penn and Charlize Theron called it quits, and the actress seems to be doing well on her own.

Charlize Theron Explains Why Sean Penn 'Fell In Love' With Her

On Friday, Daily Mail spotted the Mad Max star as she was on her way to a spin class in West Hollywood dressed in exercise attire. She wore a black and white top with workout pants as her hair was tied back and she held a bottle of water.

For the most part, her mood seemed to be solemn yet contemplative as she headed for a good workout at the gym.

Did Sean Penn Attend A Concert Solo?

Check out the pictures here.

The news of Theron and Penn came as a surprise since the actress recently gushed over her then-boyfriend and why he developed feelings for her.

"I was happy when I met Sean and I think that's why he fell in love with me- because I was happy and fulfilled and had a healthy dose of love for myself- and he's the same," Theron said via Daily Mail. "He doesn't fill a hole in me and I don't fill a hole in him."

It was announced on Us Weekly that the two stars broke up and Theron may have been the one to initiate it. The two had also apparently known each other for decades before they took their friendship into a romance.

The site also mentioned that the two didn't have a "ring," but they were "committed" to each other.

Tags: Sean Penn Charlize Theron