I think I spend 1/3 of my time living in the past, 1/3 living in the present and 1/3 in the future. One would think that's well rounded, but its probably actually very unhealthy.
I live in the past when I think of all things I used to be able to do and can't do anymore. I wish I could and sometimes imagine and try, but fail miserably.
I live in the present, but not thinking about the future. I can't imagine or see a future. That's also not good.
I live in the future when I think about all the things that can wrong with my life. It's not a hopeful future, its a scary future and one I dread.
So, none of those times are particularly effective. I need to find an effective spin to put on it.
I want to remember the good times of the past, but not be sad they are not here now. I need to remember my past made me who I am today. I need to focus on the current moment. I need to accept what I can and cannot do, and be comfortable with it. I need to see a positive future. Lots of great things can happen. Heck, they could find a cure for MS. That would be the most amazing future, but even without, I can do great things. I can live a happy life.