Keep reminding yourself: "What if it doesn't fail? what if it succeed?", I think most people mind (including my own) always gravitates towards the negative outcome, maybe we just have to "train" ourselves to gravitate towards the positive.
@tamarni it sometimes feels like an uphill battle but it's just like dripping water on a rock that'll eventually crack, if you're consistent with it eventually it'll become the norm instead of the exception!
Failure can be hard. I usually try and think of failure as the baseline, especially when it comes to experimenting with new product ideas and services.
Go in with the expectation that something will fail, but that failure is absolutely imperative to finding the thing that works. You have to go through the failure in order to find the success. Then iterate on that success and fail all over again until you get it right!
That way, failure is a positive step towards success, rather than a step backwards.
I think that preparing for failure sets you on the wrong course. In other words "You aim at what you see" - I see success, but trust myself that if failure comes in from the shadows and slaps me in the face, I'll cope with it.