Winnie Cooper's stomach is shredded!"The Wonder Years" star Danica McKellar proved she really hit the gym before her new "Dancing with the Stars" gig -- and she's got the abs to prove it.The 39-year-old showed off her impressive six-pack on Wednesday as she left dance rehearsal, putting her ripped midsection on display in a green sports bra.While competitor Candace Cameron vowed to keep her costumes "modest" on the show, it doesn't look like this former child star has the same problem."I think [that's] a given with this show," she said about wearing skimpy clothes. "I'm really glad that all the rehearsing is getting my body extra tone for the outfits." So far, she's off to a great start -- scoring a 24-30 for her first dance with partner Val Chmerkovskiy on Tuesday night. Check out the video highlights above!Check out more photos of Danica and her costars in the gallery below!