Just wanting it to *end*. The Doctor understood and felt that all too well. He struggled to keep to his focus, to keep going, removing this all from Jack's conscious mind as he pressed forward.
The Master pressed in a little, mentally, attempting to bolster the Doctor, and maybe, indirectly, Jack. Drawing on deep wells of will, sheer determination verging on fury to endure and survive. What had kept him alive when his 1st cycle of regeneration had come to an end, and during the Time War.