Chris Pratt pays tribute to wife Katharine Schwarzenegger on her birthday

Chris Pratt has thanked his ‘tough as nails’ wife Katherine Schwarzenegger on her 32nd birthday (PA)

Chris Pratt has thanked his “tough as nails” wife Katherine Schwarzenegger on her 32nd birthday.

The Guardians of the Galaxy star said Schwarzenegger had been “instrumental” in his personal growth and praised her “contagious” commitment to helping people.

The American author also received congratulations from her father, former bodybuilder and California governor Arnold Schwarzenegger.

Sharing pictures of his wife on Instagram, Pratt wrote: “Happy Birthday Honey!

“You are such a wonderful wife, mother, step-mother, and life partner. I simply can’t imagine how lost I’d be without you.

“You’re beautiful, tough as nails, reasonable, deeply thoughtful, extraordinarily smart, you’re a complete boss, eternally driven and you communicate like no other.

“Thank you for everything. Thank you for being so instrumental in my growth over the past few years.

“Your commitment to helping others is contagious. I’m just so grateful for the harmony you continually bring to our household.”

The Terminator actor also posted a picture of himself and his daughter from her childhood, writing: “Happy birthday @katherineschwarzenegger ! I love you so, so much.

“You changed my life when you came into this world and it’s been better ever since – being a father, and now a grandfather, is just the best role in the world.

“I know you’ll have another amazing year and I’ll have the best time watching you succeed.”