Profound resilience seems to be less about enhancing the capacity for effort but more about enhancing the capacity for self-observation (during the effort) from a nonjudgmental, undisturbed, non-identification space.
By doing this we are changing the relationship with our effort and become better equipped for stress.
TL:DR
Long lasting resilience comes from releasing the feeling that you are the sufferer, the doer of the effort, and becoming a simple observer.
For example: While you are running (or whatever exercise you do), when you feel close to exhaustion, try to observe yourself right at that moment. Most probably you will notice a deterioration of the quality of self-observation. Because the body will produce a lot of noise through the crying “voices”, asking to stop the burden, identification with our body and inner dialogue will be very strong.
Paradoxically or not, these exactly contexts are very good for training the ability to observe ourselves in stressful situations, therefore our capacity to be more and more resilient.