While salvation can not be lost, it can be willingly forfeited. While it's true that God does not command from us something that He himself is willing to bestow upon us, God fully expects us to love like Jesus loved and to live like Jesus lived because, once saved, God has given us His Spirit, the same Spirit and nature that dwelt in Christ.
So many today teach and preach the unconditional love of God and it is true however, they fail to comprehend that because God loves us so much that He has given us a portion of Himself to empower us to love others just as He loves us. Scripture states that we are to be Holy just as our God is Holy and to be perfect just as God our God perfect. He's not asking anything from us that He Himself has not already provided for (ie. the divine nature).
How is salvation forfeited? When we willingly refuse to follow the leading Holy Spirit. Our sin grieves Him due to the fact that He has provided everything necessary to overcome our sinful tendencies when we place our complete trust in the Word of God and are willing to surrender fully to His will. Unwillingness to surrender to His will, refusing to humble yourself and repent when the Holy Spirit is calling out to you to do so, that what it means to forfeit your salvation. Keep in mind that this doesn't happen over night or after a single or handful of willing sins. However, the Bible clearly describes in Romans 1 how the Lord is willing to turn one over to a "reprobate" mind (a lost state) if they absolutely refuse to humble themselves.