This I say then, Walk in the Spirit, and ye shall not fulfill the lust of the flesh.
Galatians 5:16 (KJV)
To walk in the Spirit is ultimately a mindset. It is to identify with who we are in Christ rather than with who we used to be in the flesh. When we remember who we are—redeemed, healed, blessed, forgiven and righteous—we gain victory over the fleshly mindset and walk in the good that has already been made available.