SB 11.28.38

yogino ’pakva-yogasya
 yuñjataḥ kāya utthitaiḥ
upasargair vihanyeta
 tatrāyaṁ vihito vidhiḥ
Synonyms: 
yoginaḥ — of the yogī; apakva-yogasya — who is immature in the practice of yoga; yuñjataḥ — trying to engage; kāyaḥ — the body; utthitaiḥ — which have arisen; upasargaiḥ — by disturbances; vihanyeta — may be frustrated; tatra — in that connection; ayam — this; vihitaḥ — is prescribed; vidhiḥ — recommended process.
Translation: 
The physical body of the endeavoring yogī who is not yet mature in his practice may sometimes be overcome by various disturbances. Therefore the following process is recommended.
Purport: 

Having described the process of cultivating knowledge, the Lord now gives instructions to the yogī whose body may be disturbed by disease or other impediments. Those inferior yogīs who are attached to the body and bodily exercises are often incomplete in their realization, and thus the Lord here offers them some assistance.