Wherefore, my beloved, as ye have always obeyed, not as in my presence only, but now much more in my absence, work out your own salvation with fear and trembling. - Philippians 2:12
This is what I have been calling "the walk" wherein our hopes turn into blessed assurance as all the doubts fall away, one by one, as we overcome - by Him - the rigorous trials of being yet in the flesh while alive in Him (Col 3:3).
It is something we do with Him, personally and intimately, because by ourselves, we can do nothing:
I am the vine, ye [are] the branches: He that abideth in me, and I in him, the same bringeth forth much fruit: for without me ye can do nothing. - John 15:5