Fluids in a bike, such as engine oil, disc brake fluid and engine coolant (in liquid-cooled engines), are integral to its smooth and reliable functioning, so every week, it is necessary to check that the levels of all the fluids are all above or at the recommended level. For recommended fluid levels and checking methods, refer to your bike's user manual.
If the fluid level is below the recommended mark, it is best that you top-up that fluid to the correct level before riding. Failure to do so might increase the chances of engine overheating (in case of low engine-oil or coolant level) and brake failure (in case of low disc brake fluid level)
Make sure to keep a can of the engine oil, brake fluid and engine coolant in stock at home, for topping up as soon as you detect low fluid level. Please refer to your bike's user manual for instuctions on topping up.