Kim Kardashian is a girl on a mission. The new mom is reportedly "obsessed" with dropping her baby weight and has picked up a new fitness regime to help. According to Hollywood Life, she now goes on hikes with her little sisters Kendall and Kylie Jenner.

She tweeted about the hike writing: "Beautiful way to end the day! Hike with @kendalljenner and @kylie jenner blacchyna." She also posted a photo of the California Mountains.

Her mom Kris Jenner said on her talk show that Kardashian was working really hard to lose the weight by "eating really well, working out a little bit and nursing." A source told the celebrity website that the "Keeping Up With the Kardashians" star has been frustrated because the weight is dropping off as fast as she thought it would.

According to one rumor she was trying to lose 30 pounds in 30 days and was desperately trying to reach her goal weight of 115 pounds.  

"As far as Kim's weight is concerned, she's got a ways to go," the source said.  "She lost quite a bit of weight initially when she first started breast feeding, but it's especially tough losing those extra baby pounds. She is still breast feeding and wants to continue for as long as she can."

According to Parents.com tons of celebrity moms go on hikes to help drop the baby weight quickly. Halle Berry's trainer, Ramona Braganza, helped the star get red carpet ready three-and-half months after she gave birth to her daughter Nahla.

"We started out conservatively, with just some cardio and stretching, five days a week," she said. "After a week, we changed it up. We'd go for hikes, a jog on the beach, or do kickboxing or yoga."

Kardashian is reportedly working with fitness guru Tracy Anderson who has the realty star on a strict diet and rigorous exercise program.