Time

Time is an enigma.
When I predict there are lots of time, then later, I find out there aren't much left. But when I feel there aren't time, then later I find that there are still some.
Also, when I concentrate on something, time passes so fast, but when I'm in bored, time passes very slowly.
I thought the "speed" of time is uniform, but may be not. At least in my world (the world I am seeing through my mind) , the speed of time is absolutely not uniform. Perhaps there are two kinds of time; one is the time measured by clock and another is the 'time' measured by one's mind. Each may have it's own speed, and the difference between these speeds could be our perception towards time.