"She feels great about many things that she has accomplished so far," a source tells PEOPLE

By Jodi Guglielmi and Melody Chiu
April 18, 2019 03:24 PM
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Kourtney Kardashian is entering a new phase in her life — and it’s full of happiness.

As Kardashian celebrates her 40th birthday on Thursday, a source tells PEOPLE the reality star is embracing the milestone occasion and what the next year could bring.

“When she talked about turning 40 a while back, she didn’t seem too excited,” says the source. “Turning 40 is a big deal. But instead of seeing it as something negative, Kourtney turned it around and she seems very excited about her life just in general.”

After launching her lifestyle website Poosh last month, the source says Kardashian has a newfound sense of pride in her work.

“She feels great about many things that she has accomplished so far,” says the source. “She is very excited about Poosh. She has been very focused on it. She has a small team that helps out, but she’s putting in many hours making sure her site is fun, educational and features brands that she loves.”

While her professional life soars, Kardashian is also content with her personal life. A second source tells PEOPLE that while Kardashian is dating, she’s careful about who she brings into life now that she’s found happiness within herself.

“Kourtney likes having someone in her life. She loves being a mom and that’s always her priority, but she can get lonely too,” the source says. “She goes on dates and has fun, but she doesn’t have a boyfriend and would never call any of these guys her ‘boyfriend.’ ”

“She’s been through a lot, personally, over the last decade and feels she’s come out stronger and happier,” adds the source. “So she’s excited about turning 40 and what’s to come.”

RELATED VIDEO: Kourtney Kardashian Shows Off Her Figure in Sexy Bathtub Snap (with Strategically Placed Bubbles)

And after years of ups and downs, Kardashian and her ex Scott Disick have managed to put their drama “behind them,” the source says, and are focused on raising their three kids: Reign, 4, Penelope, 6, and Mason, 9.

“It hasn’t been easy, but now she’s in a great place with Scott,” the source says.

Scott Disick and Kourtney Kardashian
Denise Truscello/Getty; David Livingston/Getty

On Thursday, Kardashian woke up to personalized messages from sisters and mom Kris Jenner to help kick off her birthday.

“Happy Birthday Kourtney!!! I can’t believe you are 40!! I love you more than you can ever imagine…you will always be my baby,” Jenner, 63, captioned a slideshow of photos on Instagram. “I am so blessed beyond words to be your Mommy and have you by my side in this precious life…you are my heart and I am eternally grateful for all of the memories that we cherish. I love you. Mommy xoxo.”

Sister Khloé Kardashian, meanwhile, gushed about the “rare bond” she shares with her eldest sister.

“Happy birthday sweet @kourtneykardash!!! I am completely obsessed with each and everyone of my siblings. Still blows my mind how blessed we are to call each other sisters. You and I have an incredibly rare bond that no matter what, it can never be broken,” she wrote. “You’re my best friend, one of the rare few I can count on most in my life. I’m so thankful for that.”

She continued: “I know that so many people go through life without their sister as their best friend, or without a sister in general and I don’t know how they do it. Honestly, without you my life would be boring and not as full. Today and every day, I pray that your soul is awakened and from your core, you’re happy! You deserve only magical things for the rest of your life! In all of the lifetimes before and in all of the lifetimes after I will love you! To the happiest of birthdays my sweet sister!! Jane or Suzanne (I forget who’s who) I love you!”