Sounds like it could be ADHD, inattentive type. This type of ADHD describes the kind of person who is very easily distracted, dreamy, and generally spends so much time in their own head that they are distracted from their own life. Edit: It also depends on why you spend so much time thinking about the future. Is this the result of worry, and trying to prepare for all possible scenarios? Is it fantasizing? Is it compulsive, or can you stop when you need to focus? Does it cause stress/problems in your life? This would give a more complete idea of how to understand what you're describing.

Is this the result of worry, and trying to prepare for all possible scenarios?

Yes, I worry a lot about my future.A tiny flashback of my life , makes me start thinking about my future with anxiety.You are absolutely right, I keep myself mentally and emotionally prepared for all situations.Pessmism lies in my core disposition - this is why I always think of the worse case scenario and somehow try to simulate it every now and then so that if that turns out to be real, atleast it won't be a huge shock to me.

Is it fantasizing ?

I use it as an escape mechanism.When anxiety or disappointment kicks in, the first thing that I do is take refuge to imagination which helps me cope.

Is it compulsive, or can you stop when you need to focus?

95% times it's compulsive.It's very rare for me to shut my mind off this imaginary mode.

Does it cause stress/problems in your life?

Yes, I have been skipping a lot of things.I procrastinate in spite of knowing detrimental consequences of not doing things right on time.This wasn't the case few years back - people knew how punctual I was at everything, and today, I am always late behind at everything.

To give you an example - I don't rely on myself.I mean, I spoke to a tax consultant as early as February, and he did prepare my taxes, all I have to do is file it by mailing it.But guess what, every now and then when I hear taxes and get a reminder that I need to mail the envelopes lying in my drawer, somehow I think about doing a final review and going to post office.Thats it - all this happens in my head, and once I am out of this imaginary mode, I don't even bother to open the dryer and lift envelope.I don't know if it's laziness or something wrong out in my mind.But that's how I struggle spending time little in reality and endlessly in my head.

To give you a perspective, I wake up tired, I hate to sleep, as even in my sleep all I do is thinking, be it worries or thoughts about mundane experiences of the day. Thanks.