Obviously a group less concerned about the long-term health of their interrogatees have a lot more flexibility in methods, and training is largely understood to be a delaying tactic to spoil time-sentitive tactical data, rather than resist interrogation indefinitely.
Hypothetically, there could be a mechanism by which he has to check in with some associates periodically, who by means of some N of M secret sharing are able to destroy/release the data otherwise. Then you need to resist for only 1-2 checkin periods. Or have a duress codeword that causes the same result. Any destruction scheme requires that the data be held somewhere secure enough not to be cloned though.
(And any heartbeat type scheme requires periodic communication with some/all associates, possibly leading your adversary to them, although broadcast media is probably good enough while he's mainstream news)
[1] https://en.wikipedia.org/wiki/Survival,_Evasion,_Resistance_...
[2] https://en.wikipedia.org/wiki/Resistance_to_interrogation
> You'll break. Instantly. So spare yourself the agony. Just spill the beans.
1) Write some software that destroys your data if you don't login every x hours.
2) Under duress, stall for x hours.
Other methods:
A) Alternate password that destroys the data.
B) Cyanide capsule in tooth.
Edit:
I already mentioned SERE training in a higher level post. It's pretty intense, but still, the most valuable lesson you learn is that everyone will end up talking.
I was simply commenting on the possibility of a person resisting torture. If that person has some sort of safety mechanism in place, the torturer might not be able to get the information he wants, but that's not because the victim has resisted, because he won't.