A big happy birthday to Kate Gosselin, who turns turns 36 today! Love her or hate her, this reality television star's fitness has definitely changed over the years. Below is a timeline of Gosselin's transformation from mom-next-door to trim, tanned cover model of tabloids.

2004: Staying Healthy During Pregnancy

After fertility treatment, Gosselin gives birth to sextuplets, bringing her total child count to eight. At this point her health was more of a concern than her fitness, as carrying sextuplets is an incredible feat.

2005-2007: Focusing on Family

The Gosselin family is featured in the special Surviving Sextuplets and Twins on Discovery Health in September 2005. A similar follow-up show is filmed one year later. High ratings from the specials prompt Discovery Health to sign Kate and her then husband Jon to the reality series Jon & Kate Plus 8. After two seasons the show moves to TLC. During this time Gosselin's fitness is on the back burner (or at least not in the tabloids), as she focuses on raising her brood.

2008-2009: In-Shape Mama

Amidst rumors of affairs, Jon and Kate Gosselin file for divorce. Around the same time, she is photographed in her bikini looking trim and toned. Gosselin credits running for her slim-downed body, yet tabloids suggest that she's had cosmetic surgery.

2010: Dancing Queen

Gosselin lands a spot on the popular show Dancing With the Stars. Despite a lukewarm reception by viewers, the show helps her get even more fit and toned. After the show, Gosselin takes it to whole new level though, gracing the cover of People in September 2010 in a bikini declaring, "I'm in the best shape of my life." She credits her bikini-ready body to regular runs and interval training.

Present: Birthday Girl

Today, Gosselin maintains her bikini body, recently stepping out in a little black dress with tanned and toned legs for her 36th birthday. The new season of Kate Plus 8 airs next month, and we're hoping they show more of her current fitness routine.

No matter what you think of her parenting style and time in the spotlight, one thing is for sure: She looks darn fit.