roll over and play dead
To give up the will to try/the will to fight/or possibly stay silent/take the path of least resistance - but mainly to choose for whatever reason to throw in the towel on a situation where progression seems too difficult/daunting - my take on it anyway
Initially Tony could not face the thought of all the pain/work involved in reclaiming his life and mobility after his traffic accident .. So for awhile he could only 'Roll over and Play dead like a wounded animal may do.