Kate Middleton is a well-known advocate for causes that support children's mental health. Accordingly, she's taking the time to recognize the efforts of children's hospital workers during the COVID-19 crisis.

The Duchess of Cambridge penned a beautiful letter to Evelina London Children's Hospital earlier last week. The hospital has just now shared Kate's letter.

Catherine, Duchess of Cambridge, hosts a Gala Dinner for Place2Be at Buckingham Palace in 2020.

RELATED: William & Kate Reveal Parenting Struggles During Lockdown

The Duchess of Cambridge writes to a children's hospital

Kate's letter emphasizes her appreciation of children's hospital workers - whose workplaces have intensified amid the pandemic.

"I am writing to let you know how much I am thinking of all the team at Evelina London during this hugely difficult time," the letter began. "It is heartening to know you are still very much open for business and continuing to provide expert care to sick children despite the challenging circumstances."

"You are all truly inspirational and I know how much you will be there for these families, as you always have been. You are now facing the additional pressure… but it is a testament of your support and commitment to your patients that you are all pulling together to ensure they will have the best possible care."

See the letter, on Kensington Palace paper, below! 

Kate Middleton's letter to Evelina London Children's Hospital

RELATED: Kate's Children's Mental Health Week 2020 Message

Evelina London posted Kate's letter on its Twitter account on April 20. In the caption, they identify the Duchess of Cambridge as their Patron HRH.

Kate is also a Patron of Place2Be, and she launched Children's Mental Health Week in 2020. Of course, she's also a mother of three of her own children: George (6), Charlotte (4), and Louis (1).

What a lovely picture: Check out Cambridge's 2019 Christmas Card.