For me it was different. I didn't have the luxury of thinking about it first. It's not that I regret my decision, I'm alive after all and I think the life I have now is better than being dead. But if you had the chance to think about what you really want, you should take as much time as you want. That wasn't an option for me.
Actually that might not be the best idea. If you use your wish to grant someone else's you should be careful to know exactly why you're doing it. Are you doing it for someone elses benefit, or the opposite? Your doing it for someone else's everlasting gratitude. The motive behind a wish is what matters most, you know.