I was recently challenged to read a bilingual book in several weeks. Which is less time than I would normally take to read that type and size of publication. It turned out to be an interesting and rewarding experience.
Not only did I manage to complete the book on time, but the challenge motivated me to read more. I found that it helped me focus on grammar and words that I knew, and even introduced me to some new words often enough that I can remember them now.
This got me thinking of other possible challenges. I could challenge myself to learn fifty new words in a month, or to watch videos on a topic every day for a week and explain the ideas to a friend. Maybe even a speaking exercise, trying to speak about a different topic each day for a week or two.
Short-term goals can be more motivating than endless, aimless learning, and so produce better results.