In all my looking forward and in all my worrying, it's remembering this that gives me a sigh of relief and a moment's peace:

We can, each of us, only call the present time our own…
Our Lord tells us to pray for today, and so he prevents us
from tormenting ourselves about tomorrow.
It is as if [God] were to say to say: “[It is I] who gives you this day [and]
will also give you what you need for this day.
[It is I] who makes the sun to rise.
[It is I] who scatters the darkness of night and
reveals to you the rays of the sun.

~ Gregory of Nyssa, on the Lord’s Prayer