Crying toddler lights up when visiting baby sister

Heartwarming video going viral on YouTube

It's the video that could melt the coldest of hearts.

A crying 3-year-old was having the worst day, until she sees her sister and life changes for the better.

Esther Thompson shared the video of her daughter Ellia's interaction with newborn Tessa after the 3-year-old woke up sobbing from a nap.

Thompson had already been up all night with the baby and was sure the day was going to get worse.

So when she began recording the testy toddler to send to video to her husband, something incredible happened.

Once Ellia noticed her baby sister, her mode lightened and she became happy as she began to hug Tessa.

Adorable Ellia stopped crying and said "I love her so much" and kept on saying it.

In a flash, a moment that could have been one to forget is now one to remember for a long, long time.