The thing about life is that it's ever-unpredictably-changing and even if you think you have a plan... you're wrong, and life has a rather harsh way of showing you that.
Usually when everything seems to be going great, and everything's perfect -that, that's when it'll hit you... when it's the least expected.
So embrace it. Accept it. Go with it.
Hell, fucking run with it and make the best out of it!