All experiences quoted in Csikszentmihalyi. 
An expert rock climber:
You are so involved in what you are doing, you aren’t thinking of yourself as separate from the immediate activity ... you don’t see yourself as separate from what you are doing ....
When I start on a climb, it is as if my memory input has been cut off. All I can remember is the last thirty seconds, and all I can think ahead is the next five minutes.
Your concentration is very complete. Your mind isn’t wandering, you are not thinking of something else; you are totally involved in what you are doing. Your body feels good. You are not aware of any stiffness. Your body is awake all over. No area where you feel blocked or stiff. Your energy is flowing very smoothly. You feel relaxed, comfortable, and energetic.
I get a feeling that I don’t get anywhere else.... I have more confidence in myself than at any other time. Maybe an effort to forget my problems. Dance is like therapy. If I am troubled about something I leave it out the door as I go in (the dance studio).
I am really quite oblivious to my surroundings after I really get going. I think that the phone could ring, and the doorbell could ring, or the house burn down, or something like that ... when I start workmg I really do shut out the world. Once I stop I can let it back in again.
Loss of Ego:
You yourself are in an ecstatic state to such a point that you feel as though you almost don’t exist. I’ve experienced this time and time again. My hand seems devoid of myself, and I have nothing to do with what is happening. I just sit there watching it in a state of awe and wonderment. And it just
flows out by itself.
Altered sense of time:
Time passes a hundred times faster. In this sense, it resembles the dream state. A whole story can unfold in seconds, it seems. Your body is nonexistent-but actually your heart pumps like mad to supply the brain....
Mastery and confidence:
If I have enough space, I am in control. I feel I can radiate an energy into the atmosphere. It’s not always necessary that another human being be there to catch that energy. I can dance for walls, I can dance for floors ... I don’t know if its usually. (dancer)
A strong relaxation and calmness comes over me. I have no worries of failure. What a powerful and warm feeling it is. I want to expand, hug the world. I feel enormous power to effect something of grace and beauty (dancer).
I get a tyrannical sense of power. I feel immensely strong, as tho I have the fate of another human in my grasp. I want to kill! ... I like getting lost in an external situation and forgetting about personal crap-I like being in control. Although I am not aware of specific things, I have a general feeling of well-being, and that I am in complete control of my world.(chess player)
One doesn’t do it for money. One does it for, perhaps, the satisfaction it gives. I think the great composers, all the great artists, work for themselves, period. They don’t give a damn for anybody else. They primarily satisfy themselves ....If you get any fame out of it, it’s when you are dead and buried, so what the hell’s the good of it.... This is what I tell my students. Don’t expect to make money, don’t expect fame or a pat on the back, don’t expect a damn thing. Do it because you love it.
- Csikszentmihalyi, Mihaly. “Play and Intrinsic Rewards.” Journal of Humanistic Psychology 15, no. 3 (1975): 41-63.