How do you actually finish an online course?
Schedule fixed learning slots in your calendar (two or three short sessions a week), tie the course to a concrete goal with a deadline, and make it social: tell someone what you are learning or find a learning buddy. Motivation follows rhythm, not the other way around.
It is the open secret of online learning: most started courses are never finished. Not because people are lazy, but because a course without a schedule, classmates, or deadlines runs entirely on self-discipline. That is fixable with structure.
The calendar approach works best: block fixed slots (Tuesday evening, Saturday morning) and treat them as appointments. Short, regular sessions beat binges: twice a week for 45 minutes keeps the material warm, while a lost month means starting over. Platforms help: DataCamp and Brilliant are built around short daily practice, and streaks turn out to be surprisingly motivating.
Make it concrete and social too. A goal like "my first Python project live in March" pulls harder than "learn to code someday". Tell a colleague or partner what you are working on, or better: agree on what you will demo. And pick courses with projects; building something gives the satisfaction that watching never will.