Spirit - Steadfast or Wavering?

Psalm 51:10 (NASB) “Create in me a clean heart, O God, and renew a steadfast spirit within me.” According to the Amplified Bible, this verse is rendered, “Create in me a clean heart, O God, and renew a right, persevering, and steadfast spirit within me.”

Is a right spirit based on proper alignment of external circumstances or inward renewal of a right relationship with God? If I depend on external circumstances for renewal, I might as well give up; therefore, the answer has to involve my relationship with God. If self-help were the answer to renewal, then I am ignoring the relationship component.

Can my understanding of a steadfast spirit be correct if I believe this is a goal to be aspired to rather than a destination where I am to reside? To ask God to renew the steadfast spirit would indicate to me that the writer has possessed the steadfast spirit in the past and is asking that it be renewed, as if he had lost it and needed it to be renewed, so it must be God’s ideal for us. As a sinner, I may not attain, but I should aspire for a steadfast spirit.

Romans 8:6 (NIV) “The mind of sinful man [Or mind set on the flesh] is death, but the mind controlled by the Spirit is life and peace;”

When I am troubled in spirit and not at peace, I must seek to let go of whatever is troubling, reducing my control, and allow the Spirit to be in control. I understand this in principle, but am still struggling with the practice.