Everybody is different ... [Advance disclosure: Yes, I am probably weird.]
I have a healthy respect for heights - as in I don't want to accidentally fall, but I've joyously looked down over the edge of a 2,000' cliff in Yosemite. Jumping off into the void (bungee, glider, parachute, etc. - not done, but one the list ...) would certainly be a hurdle at first.
I have a deep, reflexive discomfort with my (naked) face under water at first - I think it is my hard-wired survival instinct. I now get over it quickly - a rational over instinctual control thing. Because I recognize it and understand it it has lost much of its power - more of a "startle" reaction now.
When I was first flying, I was out practicing at an other localish field that was unfamiliar, doing landings and takeoffs in a Cessna 152 (which isn't the very lightest thing around, but pretty close in common GA aircraft). There was a taxiway and row of hangers backed by trees perpendicular to the fairly narrow runway. As I was lined up, stable, and about to touch down (just a few feet off) I came abreast of that perpendicular and I was hit by a crosswind blast and almost instantly transported to the side off of the runway. Fortunately fresh training kicked in, I goosed the lightly loaded plane, climbed out and tried to restart my heart! All good.
But the later ongoing mental after-action report left me with (besides some insights about "reading" terrain and weather in advance) the thought that things could have gone
really wrong -bang- and I could have died. I realized that I
was going to die - sooner or later, and possibly notably sooner participating in elevated-risk activities. And then, I "accepted" death . I don't seek it, I strive to avoid it, I still have a strong survival instinct. But the advance acceptance of its inevitability robs much of the dread/fear/panic reaction in crisis situations and is ironically significantly pro-survival IMO.
I have tried to learn to observe, evaluate, then react. I still have stress reactions, and I'm working to be in better control, especially in the still pretty new to me, underwater environment.