Brit's boys are getting so big!

And Britney Spears couldn't be any prouder of her sons, Jayden, 5, and Sean Preston, 6! The newly-engaged pop star, 30, showed off some in-action shots of her tots on Twitter this week.

On Tuesday, she uploaded a picture of Preston, her "little Hercules," flexing his muscles and "enjoying his gymnastics class!"

The next day, she tweeted a photo of Jayden "having some hair raising fun on the trampoline."

While the boys' biological father is Spears' ex-hubby Kevin Federline, her fiance Jason Trawick plays a huge role in Jayden and Sean Preston's lives. "Jason is just amazing with the boys," the multi-platinum singer raved to Us Weekly. "They look up to him so much -- they adore him. He's their hero."