The Baal Shem Tov zy’a (quoted in Kesser Shem Tov, Ois 21) explains this pasuk as follows:
‘When you see the chamor’ – when you view your ‘chumrius’, i.e., your body, and think that it is ‘your enemy’ because physical desires are in opposition to ruchnius, you should recognize that the body is ‘crouching under a burden’, meaning that Hashem granted the body the ability to become purified through accepting the burden of Torah and mitzvos. However, it is very difficult to do this and one might think that the way to purify the body is to ‘refuse to help him’ by afflicting the body in order to destroy the chumrius.
The pasuk states that this is not the proper way. Rather, one should ‘help him’ by purifying the body with Torah and mitzvos, rather than destroying it with afflictions.