Can a prenup divide assets based on how long you stay married?

I went through a bad divorce and didn’t have a prenup. I lost a lot of the assets I spent years working for. I’m engaged to marry again and I want to protect what I have from that same situation if the marriage doesn’t work. My fiancé and I have talked about doing a prenup that lets me keep everything I have if we divorce within the first 5 years of marriage, but gradually gives my fiancé/wife more interest the longer we are married. Is it legal to put these kinds of terms in a prenup and can my fiancé and I draft it ourselves or should we have a lawyer do it?