Rom 9:16 "So then it is not of him that willeth, nor of him that runneth, but of God that sheweth mercy."

Rom 9:15  For he saith to Moses, I will have mercy on whom I will have mercy, and I will have compassion on whom I will have compassion.

Should I not rejoice over this doctrine of God's sovereignty? If salvation is contingent upon myself and my own will, where would I end up? How can I say I am at my free will and not taken captive at the will of Satan when for so many times the LORD had innumerously strived within my heart yet I persisted to sin stubbornly!