Come now, you who say, “Today or tomorrow we will go into such and such a town and spend a year there and trade and get gain”; whereas you do not know about tomorrow. What is your life? For you are a mist that appears for a little time and then vanishes. Instead you ought to say, “If the Lord wills, we shall live and we shall do this or that.” (James 4:13-15)
“Do not rely on tomorrow: your business belongs to today, for our time is not a time for just words or for acquiring property, or indeed to swagger about enjoying ourselves, or to relax in idleness. No, for the discerning it is time for action; it is the time to gather in fruits; it is the time for repentance; it is the time for everyone to supplicate Christ with all his heart.” (Babi, “Letter to Syriacus”, The Syriac Fathers on Prayer and the Spiritual Life, p. 140)
Don’t worry about being good for the rest of your life – as long as you do it today. Don’t worry about being good for the rest of the day – as long as you do it right now.