For it is we who are the circumcision, we who serve God by his Spirit, who boast in Christ Jesus, and who put no confidence in the flesh— Philippians 3:3 (NIV)
Loving and liking yourself, being pleased and satisfied with you, feeling good about your physical body, strength and abilities is godly. Finding pleasure in all you do is God given. All of that isn’t what confidence in the flesh means.
It’s when we go to the extreme of thinking that those things above are all what it takes to be complete and find real purpose and fulfillment. Life, completeness, purpose and fulfillment are found in a Person called Jesus Christ. A personal relationship with Him is a personal relationship with those qualities. It’s what Jesus Christ did in His going to the Cross, suffering and dying for our sins, then rising from the dead that assures and empowers us to truly live complete, on purpose and fulfilled. That’s our true confidence.