The 30-year-old will line up for Team GB on the start line in Sapporo on August 7 just three years after starting running competitively.
She booked her place on the plane to Japan by winning the trial in London in March, but says the prospect of making her Olympic debut still hasn't fully sunk in.
She told the Virgin Money London Marathon: "It still does feel a bit surreal, I still sometimes feel like I'm training for just another marathon, then I'm like 'oh, I'm going to the Olympics'."
"I still haven't quite comprehended how it's gonna feel when I actually get off the plane because I just can't imagine anything so it is a case at the moment of taking each day as it comes and the excitement is slowly building and building.
"Maybe by the time I get there it will have built so much I'll be ready to burst."
Davis, who works for a London-based financial management company and runs for Clapham Chasers, is funded through a London Marathon Events programme which offers direct support to athletes who sit just outside British Athletics’ World Class programmes and Futures Academy programme but who still have the potential to star at major competitions.
She said: "I'm an unsponsored, self-funded athlete so to have the London Marathon's support for things like going away to Spain physio and things like that which would all come out my own pocket it's really helpful to have that support, along with Scottish Athletics."