Kailyn shares a special moment with her two boys.

We already knew that Isaac, Kailyn Lowry-Marroquin and ex-boyfriend Jo Rivera's son, was taking his big brother duties very seriously, but we're now being treated to an inside look at how much the little man is helping out with Baby Lincoln, who was born back in November.

Earlier this week, Kail shared the Instavid below of her newborn rolling over on his play pad, while dad Javi encourages him from behind the camera with a happy "Yeah!" Isaac, who's watching the whole awesome moment transpire, can't contain his excitement and echoes his step-dad's sentiments."Yay! Yeah! Good job!!!" the tot shouts while jumping up and down and applauding his bro's big roll. COULD YOU JUST MELT?

"You did so good, Lincoln!" Isaac reiterates once he has a chance to soak it all in. If this is what Lincoln gets for a roll, we can't wait to see what happens when he takes his first steps. Bring on the marching band!

+ Check out the clip, and don't miss the Season 5 premiere of "Teen Mom 2," Tuesday night at 10/9c!

Photo: Kailyn Lowry's Instagram