Part of the joy of motherhood is sharing the big, wide, wonderful world with your child, and this weekend, Kristin Cavallari did precisely that...we think.

The "Hills" party girl-turned-parent of two took her brand-new baby boy Jaxon out for a walk in a Chicago park, and we were treated to the first batch of pics featuring the mom strolling along with her little one. Sadly, he was safely tucked away in his stroller -- bad hair day, Jax? -- but at least we're getting somewhere!

Beyond how excited we are to (almost) peep the newest member of the Cutvallari household, we're also completely taken aback by how itty-bitty Kristin has become in the five weeks since giving birth. Two successive bouts of mono didn't even give us these types of results, cardio included (though definitely not recommended while fever-dreaming). You and your fit self belong at the beach, K-Cav -- get back to that famous shoreline from whence you came!

+ What do you think of Kristin's new baby (carriage) and her unbelievably toned frame?

Photo: Splash News