"lay down our lives for the brethren": We are to present our bodies as a sacrifice of service to other believers which is our reasonable service to God (Rom. 12:1-16).
"how dwelleth the love of God in him": The love of God is shed abroad in our heart and then shines outward as we serve those begotten of God---building up the household of God so we might be as lights on a hill to those who dwell in darkness.
"deed and in truth" - Truth is the words that comprise our faith; deeds refer to our works of love in that faith. Faith that does not produce works is useless to God (Ja.2:20) as are works that are not based in truth (1Cor.3:12-15).
Picking up our cross
For Jesus, picking up His cross (Lk.9:23) meant doing the will of His heavenly Father (Lk.22:42), and so it does for us. God's will for us is to pick up our cross and serve Him by ministering his word to others; the gospel to the unsaved and words that build-up to other believers (Rom.12:1-16), even if it leads to persecution (1Pet.2:21) and death as it did for Peter (Jn.21:18-19).
Forgetting what is behind
Jesus let go of the glory He held in heaven in order to follow the Father's will for Him to serve and save the lost (Phil.2:5-7). And so Paul let go of the world's
glory,
in order to
follow the will of Jesus (Phil.3:7-8).
Pressing on
Jesus reaches out in love to the lost through Calvary's
cross
(Phil.2:8), so Paul's response is to reach out to Him by serving his Body which is a pattern for the flock to follow (Phil.3:12-14,17).
Waiting in hope
As Jesus picked up His cross to do the Father's will, He focused on the glory and joy that awaited Him in heaven (Phil.2:9), and as we pick up our cross to do the will of Jesus, we are to set our mind on our heavenly destiny
where we will receive glorified bodies and share in the inheritance of Jesus Christ (Phil.3:20-21).
To forget what is behind
I pray Thee that my mind
Be melded now with Thine
