Dax Shepard thinks his life with Kristen Bell is ''suspiciously great''.

The 45-year-old actor took to social media on Saturday (18.07.20) to wish his wife - with whom he has daughters Lincoln, seven, and Delta, five - a happy 40th birthday, and joked there must be something amiss with how ''great'' his life is thanks to the 'Frozen II' star.

He wrote alongside a picture of the pair: ''Happiest birthday most beautifulest buddy @kristenanniebell. Thank you for this suspiciously great life you've made for us (sic)''

The couple celebrated Kristen's birthday with a trip to Sedona, Arizona, with their daughters and several friends, and the actress documented their trip on her own Instagram account.

She posted: ''Sedona AZ is hot as Hades!

''Thank you for the beautiful hikes, the river swimming and the boarder line heat stroke. Our pod is grateful for the beauty this country has to offer.

''***@daxshepard had to work on (the very safe set of) #topgearamerica so our pod decided to follow him for a fun family road trip. We were extra cautious the whole time and only took our masks off when we were secluded. #staysafeamerica (sic)''

Meanwhile, Dax previously admitted he didn't ''believe in'' marriage, but agreed to make his relationship with Kristen - who he wed in 2013 after six years together - official to give her security.

He said: ''That was the hardest part about getting married for me: I was like what leverage do you have left anymore? Another wrinkle was that I fundamentally did not believe in the institute of marriage. I had been with a girl for nine years before Kristen and we were going to have a baby for sure. I was very in favour of spending your life with somebody but I was just theoretically opposed to the notion of marriage.

''At a certain point, I was like, 'She wants this really bad and this will make her feel safe.' ''