Taken from John MacArthur Study Bible (Highly Recommend)
I have been crucified with Christ. See notes on Ro 6:2–6 . When a person trusts in Christ for salvation, he spiritually participates with the Lord in His crucifixion and His victory over sin and death. no longer I who live, but Christ lives in me. The believer’s old self is dead ( see note on Eph 4:22 ), having been crucified with Christ ( Ro 6:3 , 5 ). The believer’s new self has the privilege of the indwelling Christ empowering him and living through him ( see notes on Ro 8:9 , 10 ). gave Himself up for me. The manifestation of Christ’s love for the believer through His sacrificial death on the cross ( Jn 10:17 , 18 ; Ro 5:6–8 ; Eph 5:25–30 ).