You can assign workers to production buildings (Mine, Sawmill, Farm, Forge, Workshop, and Laboratory) to speed up item production in them.
 
You can do that by going to the Town Hall or opening up item production menu, clicking on the building icon, and pressing “Add.” After being assigned, a worker can't be moved to another place for 5 minutes.
 
Workers receive experience for their help and shave even more off production time as they learn.
 
Upgrade your Town Hall to get new workers.