They make LED bulbs that fit many of the common non-LED fixtures. You need to know exactly which fixture you have and then you can check to see if you can find something that is compatible. Changing the bulb is a little bit of a project, usually easy enough if you are DIY inclined and have the correct replacement gasket to use when sealing the fixture back up.
If there isn't a bulb that fits your current fixture, you will need to find a fixture that will fit in the same niche your current fixture is installed in. That may not be so easy to find, depending on what you have now. Replacing the fixture is more complex, and sometimes leads to difficulties (when the conduit has collapsed). Still, a confident DIY type can handle it.
Changing the niche that the light is mounted in is very difficult. Most people will want to leave that project to a professional, or more likely make do with what they already have.