Maybe yes.. maybe no. It would depend on how much time is left, and if it's unchangeable.
If it's unchangeable and decades away, I might actually feel better, and do things I might not otherwise do, knowing 'well, this isn't what's going to kill me'. Then again.. the worse outcome of doing anything crazy is just getting badly hurt and living to regret it. >_> So I doubt I'd do anything TOO crazy still. But with a timeline, I might be more inspired to live life more than I do now.
If it's changeable... I'd live up to that point, and then try to alter it and avoid it.
If it's like, a year away and unchangeable, I wouldn't want to know... I would end up never doing anything and just being depressed knowing my time is that short. D: