Somebody has not known the reason of having a heater in their workshop. The answer for this question is pretty obvious: one of the major disadvantages of using your garage as a workshop or a home office is that it wasn't meant for that. The garage is the special place reserved for your car, the garage is the room where you keep your lawn and garden accessories.
If you start using this space for other projects that you have, you need to deal with one of the major inconveniences, that is warmth. During the summer you don't have to worry too much about this but during cold seasons you might find some difficulties in continuing your project because of the very low temperature.
You can find many ways to warm up your workshop- garage. You can try one of the porcelain heaters; they work great and can warm up a good area but they are not meant to warm a large space for a long time.
Another solution for you would be to use a kerosene heater. These heaters are easy to turn on
A very good and popular choice nowadays is a gas heater
There are two types of gas heaters: vented and vent less. The vent less unit uses air from the room and the vented model has a system that vents directly out of the garage. The disadvantage of the vent less model is that you have to keep the room vented at all times because the unit uses the air from the room where it has been installed. The main advantage for the both types of gas heaters is that they have a pretty low running cost compared to the kerosene and electric heaters.
Remember that if you choose to install a more advanced heating system like a gas heater, you must ask for a professional's help