How long can you concentrate on any particular topic or subject of your interest?

I remember hearing that however old we are, we should be able to steadily concentrate for the same amount of time in minutes. I'm not sure how true that is, especially for those in their later years, but it sounds good to me. :P

What?

Dang near forever.
If I start writing music, I don't stop until it's finished or until I don't even realize I've fallen asleep. Sometimes I almost wish I could just stop and take a break.
Almost.

I've spent about 12 hours straight reading with no distractions or interruptions before and I normally stay up reading for 6+ hours at night. A couple of hours is good enough for me since a lot of times my mind starts to wander - it depends on what I am doing and how interested it is. I don't like feeling as if I have to do something, if I do something it is because I want to, not because I have to but left to my own device, I can concentrate for hours at a time.

as long as i need to. or want to for that matter...could be hours...i was actuallly up for 37 hours straight trying to write a song one time...finally got it written but only after i got some sleep

Good question. It depends but it's hours, or can be...

but the work that must be done... that can be another matter

a few hours