Kristen Bell and Jenna Fischer are 30-day homies.

Bell initiated a 30-day fitness challenge on her Twitter and Fischer was brave enough to sign up with Bell's other followers. The actresses have been tweeting their complaints and messages of support as they try to reach their workout goals.

Bell, 31, explained the rules as, "Just a challenge to be active for one hour per day for 30 days. Walking, DVDs, exercise class, jog etc. We complain together!"

And complain she has!

"Spinning is the hardest thing for me," Bell tweeted on day 12. "I am by far the worst in my class, which is hilarious and embarrassing. I cried during the cool down because I was exhausted, annoyed and stunned at how infectiously nice everyone in class was. Clearly, I needed a minute. Don't give up. Let's hit 30 together."

"Dear 30-day homies — Today was terrible," she tweeted Wednesday on her 16th day of the workout challenge. "I went to a bar method class today which I normally love, but my equilibrium totally wet the bed. I barely had balance or energy — all I was thinking about was what's on my TiVo — and I honestly only did the exercises if the teacher was looking at me. I zoned out for minutes at a time. The other students must have thought I was on drugs. Oh well, there's always tomorrow. How are you all doing? Love, the captain."

Fischer, 38, who gave birth to her son Weston last September, joined Bell's challenge last Friday. "Okay, I'm on board!" the Office star tweeted at Bell. "So far this week: weights, yoga, hiking, hiking, weights. I'm thinking ab DVD tomorrow. 30-day homes."

"Go get 'em Jenna!" Bell wrote in support. "Griffith park hike is rad, and also bar method classes. We are now 30-day homies."

Fischer has previously chatted with Us Weekly about the pressure of losing the baby weight. At the Screen Actors Guild Awards in January, Fischer told Us, "Let me please stand in solidarity with all of the women who are not a size 2 six weeks after leaving the hospital. I am breastfeeding my baby and I am not getting any skinnier!"

Now, the new mom is finding ways to balance her workouts with motherhood. "Baby would only nap if I held him. Teething. Spent 2 hrs in a rocking chair. Still got in 40 minutes of cardio and 20 minutes of abs! Proud," she tweeted to Bell.

And Bell has been tweeting helpful advice to her fellow 30-day homes along the way.

"The only way your body metabolizes fat efficiently is if you're hydrated! she wrote. "Your Body rids itself of fat through sweat, C02 and urine. So make sure to drink lots of H20 and pee a lot!"