The verse says "all flesh"...
Think of "All Flesh" not just as "all mankind."
Think of "all flesh" as in every bit of my being ... all that I am.
Include every single atom that comprises my being...
Include every thought,
and every longing.
All that I am, with all my past and all my future, is invited.
All I bring He takes and I am made welcome.
It is not a case for our human striving but of recognising that our mind cannot take us to the realm of the Spirit.
It is a coming to God with an open heart that He may do for us what we could never do for ourselves.
May He find us bringing our all before Him in longing - that as His Spirit-born creatures we may find Completion in Him.