You may be using a lot more hard drive space with Lightroom than you need to be. There are three major opportunity areas: catalog backups, 1:1 previews, and deleting rejects.
My Lightroom catalog is about 500 MB. (To see how large yours is, go to Edit>Catalog Settings on the PC, or Lightroom>Catalog Settings on the Mac. The size is listed on the General tab.) If I do a catalog backup once a week, that is 26 GB of catalog copies that I am adding to my hard drive every year. If I do a backup every day, that is 182 GB per year! It is important, therefore, to go in and clean out old backups. I like to keep a few backups in case my catalog already had corruption issues during my most recent backups. I keep one a day for a week, one a week for a month and one a month for a year.
If you are not sure where your backup catalogs are, next time Lightroom prompts you to back up your catalog, note in the dialog where they are going. In Finder or Windows Explorer, navigate to this folder. You will see a folder for each date — delete these date folders.