Jason Priestley has started to "think about his own mortality" after the death of Shannen Doherty.
The 54-year-old actor starred alongside Shannen - who died in July at the age of 53 following a long battle with breast cancer - as her on-screen twin in the hit 1990s drama series 'Beverly Hills, 90210' and admitted that he was "hit hard" by the passing of his former co-star.
He told The Sunday Mirror newspaper: "It has made me think about my own mortality. I woke up on my 50th birthday and I realised that I’d already lived most of my life. Her passing hit me hard. We had an incredible experience working together... it was the day Shannen, Luke [Perry] and I were shot for the cover of Rolling Stone [in 1992] that I started to understand the impact the show was having."
The former 'Private Eyes' star remembered Shannen as being "very open" about her health battles and commended the 'Charmed' star - who spoke candily about her illness through her 'Let's Be Clear' podcast - for her determination to help others as he admitted he felt "very fortunate" to have been able to spend time with her in those last moments.
Jason - who has Ava, 17, and 15-year-old Dashiell with wife Naomi Lowde-Priestley - added: "She was very open about what was happening with her cancer and tried to use her platform to help other people. I always admired her tenacity and her toughness, so even though I knew she was sick, her actually passing away was a big surprise, and sad for all of us. She fought it for so long and seemed like she was able to manage it... until she wasn’t, unfortunately.
"Shannen was a force. And I feel very fortunate that in the last couple years, I got to spend quite a bit of time with her. I felt okay about her passing in so much as there was nothing left between us that was unsaid."
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