"forgetting those things which are behind"

can be a very difficult thing to do!

But probably much much more difficult taken out of context . . .

Not that I have already attained, or am already perfected; but I press on, that I may lay hold of that for which Christ Jesus has also laid hold of me. Brethren, I do not count myself to have apprehended; but one thing I do, forgetting those things which are behind and reaching forward to those things which are ahead, I press toward the goal for the prize of the upward call of God in Christ Jesus.

Therefore let us, as many as are mature, have this mind; and if in anything you think otherwise, God will reveal even this to you. Nevertheless, to the degree that we have already attained, let us walk by the same rule, let us be of the same mind.
-- Philippians 3:12-16