Matthew 6:33-34 “But seek first the kingdom of God and His righteousness, and all these things shall be added to you. Therefore do not worry about tomorrow, for tomorrow will worry about it’s own things. Sufficient for the day is it’s own trouble.”
It is easier to have joy when you do not look to the past or to the future; one which you cannot change and the other which you cannot know. For we are not God – our reach is only as far as our presence, and that only exists in the present.