everyone experiences pain differently
nitpick time again - everyone experiences pain the same, it's how you react that differs.
OK, Craig & Ruth, damn you for noticing the "enduring" phrase which I missed. Agreed, prolonged exposure to pain shouldn't be necessary, but temporary's good for the soul - just remember 'tis better to give than receive...
Ruth, can you give me an example of pain=barrier? The only one that I can think of for people who actually remain within aikido is ukemi-fear. If someone is unable to accept any pain (and they exist in strangely large numbers) they don't seem to continue to practice, so I wouldn't include them in the poll...
(mental pain - isn't that the true reason behind beer waza?)