The Buddha's Five Remembrances:

I am of the nature to grow old.

There is no way to escape growing old.

I am of the nature to have ill health.

There is no way to escape ill health.

I am of the nature to die.

There is no way to escape death.

All that is dear to me and everyone I love are the nature to change.

There is no way to escape being separated from them.

My actions are my only true belongings.

I cannot escape the consequences of my actions. My actions are the ground upon which I stand.