If we are the ones who save ourselves, we can surely lose our salvation. I did not save myself. Jesus saved me. Salvation is God's business. Revelation 7:10 says "salvation to our God....." Some versions include "belongs" as it is obvious that God does not need saving. Psalm 3:8 says "belongs."
If salvation depends on how diligent, how faithful, how obedient and how good we are, no one would be saved. No one is that good and no one but Jesus has ever lived the life that perfectly pleased God. He now represents the believer to God and God accepts us because we are hidden in Christ with God. I don't have to try to be crucified with Christ. I can't anyway. I could nail my feet and one hand, but that's it. So God does it all perfectly in Christ. All we do is receive with joy and learn to live in the light of that great salvation.