If your workshop is in an unfinished garage or basement and not attached to your central heating system, your best option is to make use of space heaters.
Cool Tools brings us two of their favorites that cover a lot of different applications and one of them should work for you.
ProCom Unvented Propane Heater
A combination radiant/passive-convection heater powered by propane, the ProCom burns cleanly and needs no vent or chimney.
Dyna-Glo Pro Heater
It’s very powerful (70,000 BTU) and, amazingly, creates no detectable odor while burning kerosene.
Don’t forget these space heater safety tips.