Carrie Underwood's Birthday Tribute to Her 5-Year-Old Son Isaiah Proves How Fast Time Goes

Carrie Underwood's family is celebrating a big milestone! Isaiah, Carrie's oldest son whom she shares with Mike Fisher, turned 5 years old on Feb. 27. The country singer shared a heartwarming throwback on Instagram in honor of the big day, and yes, time with kids certainly moves fast.

"He is five today. Where did these last five years go? It's so bittersweet watching your children grow up," she wrote. "You want them to stay little and chubby and cuddly forever but it's also so much fun seeing them turn into little people! Isaiah, you are funny and smart and such a caring little boy! You already have so much love for God and for all those around you. The day I became your mother was the day my life changed forever. You are five today but you will always be my baby boy . . . no matter how old you get. Thank you for being you."

Aw, how sweet! Happy 5th birthday, Isaiah!