This is the joy you feel when you're 13 you can finally dress yourself

Until I had a child with cerebral palsy, I never thought twice about the ability to pull on pants, button a shirt or zip up a jacket. Then I had Max, and it became clear when he was a tot how challenging using his hands would be.

Therapists spent session after session on the basics, coaching him how to push buttons on toys, grasp balls and blocks and hold a spoon. They showed me how to position his pudgy little fingers around objects, and how to hold my hands over his so I could teach him the movements for throwing and catching.

As the years passed, Max has been able to do more and more with his hands. He can hold playthings and feed himself, and he is a whiz at navigating around the iPad. Yet getting dressed remains a major challenge, holding him back from independence. His fingers do not have the dexterity to close buttons; consider the precise movements involved in that one small action. He doesn't yet have the coordination to hold a shirt and slip his arms in. Manipulating pants is an issue, too.

What makes things even trickier is that Max tries to do everything with his left hand alone. The stroke Max had at birth affected both sides of his brain but was bigger on his left side, so his right hand is the weaker one. Typically, he rests it on his stomach or chest and forgets all about it. "Use two hands, Max!" we're always prompting him.

I was really excited when Mindy Scheier—a designer, mom to a son with muscular dystrophy and founder of the nonprofit Runway of Dreams—teamed up with Tommy Hilfiger for a line of adaptive clothing. A couple of weeks ago, we got a shirt from the new collection. It looks like any other stylish Tommy clothing, except the buttons on the front and cuffs of shirts and on the fly parts of pants hide magnetic closures.

I helped Max get his arms into the sleeves. And then, instead of buttoning his shirt as I've done for him all these years, I let Max take over.

At first, he had a hard time lining up the closures, and the shirt kept going on askew. I'd open it back up, and he'd try again and again and again because this boy has the gift of super-determination. (Not to mention: good hair).

And then, he got it. The joy he so clearly felt about closing that top with his own two hands (OK, one hand) just about made me burst. Max giggled in excitement; I gasped because I was choking back a sob.

Were there ever more satisfying "clicks!" in the history of clicks?!

I can't know exactly how it feels to be 13 years old and finally be able to close your own shirt. But I can say that as Max's mom, I felt relief, pride and the thrill of a major win.

And hey, Tommy Hilfiger: If you're looking for a model for your next collection, Max is available! Although you may have to pay him in chocolate milkshakes.