This investment is low risk, high return.

It is the single greatest investment you can ever make.

To make this investment would be wise.
To not make this investment would be a tragedy.

It is the single greatest investment you can ever make.

This investment should not be a choice but, instead, a responsibility.
What you have to gain by making this investment far outweighs what you have to lose.
Though this investment will yield a high return while you are living, it will yield an even higher return when you are gone.

It is the single greatest investment you can ever make.

This investment will bless you.
This investment will satisfy you.
This investment will outlive you.

So what, exactly, is this investment in?

People.