The new series started last week on Channel 4 as another two groups took on the challenge of surviving alone on uninhabited pacific islands.
After two weeks, one contestant has already quit after finding the going too tough.
But Bear reckons those who choose to leave will always regret it.
Speaking about contestants quitting the show, Bear said: "I get frustrated for them. You only get one opportunity at this and you looked me in the eye and you told me you wanted to show to your kids what you're really made of or you wanted to show to your husband what you're really made of. Don't quit!
"I told you this is going to be grim. I told you you'll feel like quitting. I told you that the pain doesn't last forever. They're not just words, believe me. Now walk in. But that is the show. You put them in those conditions and some crumble and some thrive."
Talking to DigitalSpy about past series, Bear revealed that those that quit regretted their decision, having spoken to them since they left The Island.
Saying he felt "disappointed for them", Bear explained: "I've seen them since - and they're like, 'Oh, what was I thinking?' It's now out there forever and the world is going to see.
"The other people don't remember the sandfly bites - they're busy eating pizza and celebrating and chinking glasses, 'Wheeey, we're the heroes!' You're the heroes because you went through the pain. But you can't get a hero without the pain."
The Island airs Monday nights at 9PM on Channel 4.