"Help shall you help with him" — the Torah commands assisting someone whose animal is struggling. But the Mekhilta distinguishes between two different types of assistance: unloading a burden from a struggling animal, and loading a burden onto an animal that needs to be loaded.
(Deuteronomy 22:4) says: "Lift up shall you lift up with him." From this doubling — "lift up shall you lift up" — the Mekhilta derives that the obligation includes not just handling the load but lifting the animal itself when it has fallen.
But there is a crucial qualifier: "with him." You are obligated to help with him — meaning alongside the owner. The obligation is cooperative, not unilateral. If the animal's owner sits down and says, "Since you are obligated to help me, do all the work yourself," you are not required to comply.
The owner must participate. He must do his part. The Torah commands you to help with him, not instead of him. If the owner refuses to work alongside you, your obligation is discharged.
This "with him" principle prevents the commandment from being exploited. The Torah does not create an obligation for one person to do another person's labor. It creates an obligation of mutual assistance. Both parties must contribute effort. Help is a partnership, not a service.