WATCH: Serena joins Venus in fun stretching workout

On Tuesday, Serena Williams joined sister Venus in a "Tennis Tuesday" workout session. The elder Williams sister has been posting regular workout videos and tutorials for the past two months, and this was her first with Serena joining in.

"A lot of people ask what does Serena do or maybe no one has asked what Serena does," Serena said. "But I'm assuming and I'm so full of myself to think that people do."

Before beginning the tutorial, Venus asked Serena if she is missing the tennis court at all.

"You won't believe this, but I am so so not missing the court," Serena said. The 23-time Grand Slam champion did add that she misses playing doubles with her sister.

The two then took off their shoes and headed straight for their purple yoga mats. Venus had a surprise gift for Serena which turned out to be a lavender scented "Yoga Mat Detox" cleaner.

"I kind of want to spray this on myself," Venus said.

Co-coach Serena began her routine nice and slow with a couple of neck, head and body rolls. "Some of us have big heads and know everything, so our heads might tend to be bigger than others," she said.

Her warmup routine is a little intense so she urged her fans to take breaks or sit back and drink a mimosa while watching. She would continue to lead fans around the world through an intense 25-minute routine that included hip flexer stretches, squats, hamstring stretches and arms and leg movements.

"I really want to stretch more because I feel there are so many endorphins that are released," Venus said. "I just feel so good after stretching."

Serena mentioned her stretching routine is supposed to be more of a workout and it really focuses on the quads, since she is building strength in that area. Though the 38-year-old isn't missing practice, she's ready to get back to competing because the break is the best thing to happen to her body.

For now, Serena is working hard on her health and fitness, which includes a careful diet.

"I found this incredible [cinnamon role] recipe and I said I'm not going to make it again until June 13," Serena said. "So I'm working out every day because I'm literally going to eat all 12 when I make them again. I'm not even kidding."

"That's 6-0, 6-0," Venus pointed out.

Venus will be back to her usual programming for Instagram Live Wednesday with more fitness for fans.