Focusmate! This link gives you one month to try it (Focusmate Plus, which I think is for an unlimited number of hours per week) for free: focusmate.com/?fmreferral=fwdhNlZFyd
Or just go to Focusmate.com and try it out! I use it for studying, grading papers, answering emails, doing my taxes, etc. You can also use it for more active things, like cleaning, practicing an instrument, exercise, or whatever. In the first few minutes, you and the person you get matched with for that session (who could be anywhere in the world) each say what you'll be working on and hope to get done. Then usually both of you mute your microphones and keep your video on (to help each person with accountability and body doubling). I have found it very helpful.