I don't know what I don't want

I was talking to this director from a HR consultancy firm last week and I remember two things he shared:
1) The three critical period people tend to leave their jobs - first year, third year and fifth year. After the fifth year, people tend to stay with their firm for a longer period.
2) People need to know what they don't want to do so they can know what they want to do in their career.

I guess they stuck in my mind because:
1) I'm turning 4 in my current job so the next critical period is approaching.
2) I'm not sure if what I am doing (or which part of it) is what I don't want to do.

For me, 1) is good - it reminds me that it is time to review my career plans and 2) is scary - how am I going to review my career plans if I don't know what I don't want.

I have this feeling about busy doing nothing in the past year. I'm busy but when I look back, I'm not sure what I have really achieved. Perhaps it's because I don't know what I don't want.

But I know it's time to do something about this.