Agents of S.H.I.E.L.D., Season 5

Peterson:
Nightmare? This whole thing has been a dream. And every time the dream is too random or doesn't reconcile with a memory, your mind creates a scenario to make it work.

Coulson:
See, now you're losing me.

Peterson:
What does that even mean? You really think your skull is caught on fire, Phil? Or does it hurt to have electrodes on your scalp for this long? You think there was an alternate reality where you were a history teacher? Or were you remembering your father, who was a history teacher?

Coulson:
Okay, stop.

Peterson:
You're reliving mementos of your life mixed with the dreams you wish had come true.

Coulson:
No, Mike. This is fear. I thought I'd come to terms with death, but this is my fear of it manifesting, because it's harder to let go of than I thought it would be.

Peterson:
Yes. You're struggling to let go. At least now you admit you're dying. What's the hardest part?

Coulson:
The life I have yet to live.

Peterson:
And that's why your mind created this story, where you spent years doing all the things you never got a chance to do... to vacation on a white beach with blue water. To travel to the stars. To own your own plane, a car that flies, your own team. To have a family. The brilliant students you never got a chance to mentor. The daughter you never had. And above all, a chance to be a hero. You said it yourself, Coulson. It matters who you are.