It was the hardest thing I've done in my life. God used it to show me who I was - I fully needed his strength, and he taught me about myself and himself. It's the kind of thing where you absolutely mustn't do unless you're sure God wants you to. Otherwise you won't be able to cope.

You need a lot of grace. You're communicating in a language that's not your first language - all the volunteers have to learn Chinese. It levels the playing field. Not all of the brothers - that's what we call the men in the centre - speak English, and if English is all you speak, the brother who can speak English has power over the others.

I went back there after a couple of years, and seeing some of the guys who'd come off heroin while I was there the first time leading groups was one of the best things.

I never really felt in danger. I was 18 and I suppose it never even occurred to me that I was in danger. It didn't matter: God looked after me, provided for me and he protected me too. It was really challenging - and tiring. And it was good fun.

It's like any mission. You go out there, saying, "God, I'm yours," and he respects that.