Left: hand /彐, right: build, work 工 (image of a carpenter's square)
The hand that assists, (=supports with the carpenter's square) is the left.

Left: feeling 忄, right: left 左, body 月/肉
(being right-handed:) I feel that my left body (= left body's half) is lazy.

Left: sceleton 骨, right: 遀 (movement 辶, part of lazy 惰 [I feel 忄, that the left 左 [half] of my body 月 is lazy])
The sceleton has during movement sth. lazy: The marrow.

Left: person 亻/人, right: left 左 (The hand that supports when building 工)
The person at left assists.