At a canter

Easily, without effort, derives from horse riding where a canter is an easy, effortless pace. The metaphorical usage of the expression dates from the late 18th century. Canter itself is an interesting word that is first cited from the mid-18th century and is an abbreviation of the earlier ‘Canterbury gallop, pace or trot’, which was the leisurely pace associated with Canterbury pilgrims. See also Canter.