I believe their explanation is a bit more simple. That Paul is keeping his 'eye on the prize', which is heaven. In other words, he gave little importance to his pains and sufferings as a human being, as they were much less consequential than what awaited him in heaven.
Ironically, in a roundabout way, I believe they may be partially correct in this interpretation because the shift is one from physical to mental, with the importance being placed on the mental. The spirit versus the tent that is the flesh.