True change always happens on the inside. Changing your outward appearance (whether that’s your looks, your deeds or your words) is really just dressing up what’s on the inside. In order to truly change, you must change from the inside out.
Paul knew the secret to being joyful in all circumstances was found not in outward circumstances and actions, but in inward peace and action. His final chapter reads as a bullet list for how to affect change on the inside:
Do not be anxious about anything, but in everything by prayer and supplication with thanksgiving let your requests be made known to God. Philippians 4:6
Anxious on the inside? Bring it before the Lord in prayer.
Finally, brothers, whatever is true, whatever is honorable, whatever is just, whatever is pure, whatever is lovely, whatever is commendable, if there is any excellence, if there is anything worthy of praise, think about these things. Philippians 4:8
Struggling with sin? Shift the focus of your thinking.
Not that I am speaking of being in need, for I have learned in whatever situation I am to be content. I know how to be brought low, and I know how to abound. In any and every circumstance, I have learned the secret of facing plenty and hunger, abundance and need. Philippians 4:11-12
Always needing more stuff? Practice contentment.
It sounds simple, but it’s incredibly difficult. Unless of course, like Paul, you aren’t doing it on your own:
I can do all things through Him who strengthens me. Philippians 4:13