like cooking, floriculture and computer-repair?
If by manual labor you mean actually having to DO something physically, then there is no such trade. All jobs have some level of manual labor connected to them. If you want an easy job, then being in retail sales is pretty much a laborless job. All you do is pretty much stand there and convince customers to buy the products you are pushing.
Operator i.e. driving back hoes, cranes, excavators, dozers, skitters, etc.
