1Say it plainly whenever you teach anything: the way I am showing you this is not the way it has to be done. Change it until it works for you.
Anyone who has failed at the standard version of something several times will not try again unless they are told clearly that adapting it is allowed. Without that, the first awkward attempt simply confirms what they already believe about themselves. Give the permission before they start rather than afterwards, and ask later what they changed. What comes back is often better than what you offered.
Islamic evidence
God does not burden any soul with more than He has given it (Quran 65:7). What is asked is fitted to the person, so fitting a practice to a person is in good company.
“and let the wealthy man spend according to his wealth. But let him whose provision is restricted spend according to what God has given him: God does not burden any soul with more than He has given it- after hardship, God will bring ease”
Qur'an 65:7
Psychological evidence
In a randomised trial, brief mindfulness after a stressor raised heart rate variability in ordinary participants but not in people high in maladaptive perfectionism. The same practice, delivered the same way, did different things to different people. It is one study of one trait, and it is reasonable grounds for holding any protocol loosely.
Azam MA, Katz J, Fashler SR, Changoor T, Azargive S, Ritvo P. (2015). International journal of psychophysiology : official journal of the International Organization of Psychophysiology · doi
Review detail
Why it works. People who expect to fail at a technique need to hear there is no wrong way to do it before they will risk trying.