You are busy but sometimes you pause to reflect on the next half of life. 

You are wondering, like most of us at this stage in life, why you feel like the first half of life is over and are looking for something that will make the "second half" significant.

You long for a challenge but you have no idea where to begin.
Your career has been successful - fun, but you find moving up the ladder is an empty reward. You sense there is more to life than accumulating things, career achievement and lifestyle.

Or if you're in your 20's or 30's single or married with children busy and wondering if this is as good as it gets...

Or if you are in your 60's or 70's, not counting your years since you were born, but wishing to make the most of the years you have left ...