Salary is always the best motivation for work 
If you pay your worker well, you show him that you appreciate him, his work and effort.
You're right, if you pay your worker fairly its a motivation to work hard for getting what they deserves not only for them but also for their family. Plus showing that you care as an employer is important too for them to not feel that they are just a worker but a family that you care of.If you pay your worker well, you show him that you appreciate him, his work and effort.