The person setting the pace should know who is being left behind and why.

Whoever is fastest usually sets the speed without noticing they have set anything. On a walk, in a meeting, in a project, the front of the group experiences the pace as normal, and the back experiences it as strain they are failing at privately. The gap is invisible from the front, which is exactly where the decision is being made.

Look behind you on purpose if you tend to lead. Not once at the end, but during: who has gone quiet, who is half a step off, who stopped asking questions. Then ask that person what speed would work, and be willing to hear an answer that costs you something.