Above all else, guard your heart, for it is the wellspring of life (v23).
The well spring of my life is my heart - my heart should both refresh & nourish me and it will dictate my outlook in life. If the water from this wellspring is polluted or has run dry, it will have a negative effect on me and those around me. So I need to guard my heart.
I need to guard against pride & envy & jealousy. I need to guard against ranking myself against others. I need to guard against a poverty mentality and against worry.
I need to think about whatever is true, whatever is noble, whatever is right, whatever is admirable, to think about anything that is excellent or praise worthy (Phil 4v8).
I need to talk to myself more. To talk to myself about Jesus and His gospel. In so doing I will guard my heart and enjoy a free flowing wellspring that will nourish me, my family & my friends.