I once came across a prayer for middle age written by a Carmelite friar. It inspired the following blessing for someone who is beginning to grow old.

God keep you from
having to say something on every occasion,
having to sort out everyone else's affairs,
reciting endless details.
God give you wings to get to the point.

God seal your lips on your aches and pains.

God keep you reasonably sweet,
for a sour old person is one of the crowning works of the devil.

God help you to endure with patience others' tales of woe.

God give you
an ability to see good things in unexpected places,
talents in unexpected people,
and the grace to tell them so.

keep you from evil within,
shield you from evil without,
bless you with virtue and sweetness,
aid you in times of trial.

give you pluck and valor,
bring you good health and good speech,
save you for good and for God,
the One and the Three who is love.

Ray Simpson in Celtic Blessings: Prayers for Everyday Life