I agree with goal setting, and think that tangible and measurable is a lot better way to go if you want to see/hear results.
Some things are easier to measure, like "I want to be able to play ___ exercise/scale at ___ tempo with ___ bowing" vs. "I want to improve my intonation". I think both are achievable, but I feel that you have to find a way to measure intonation. Recording yourself is a great way to be able to hear progress, and I would suggest long tones, drone scales, and playing with a pianist/ensemble/recording (that features good tuning/intonation) to help you get there. I don't really know how to phrase that into a goal structure of "I want to do "x" in "y" way to achieve result "z"" though.
Personally, performances and lessons tend to be my strongest motivators. Even if it is playing for a couple of peers in your living room, performing is extremely valuable. And lessons are an expensive waste of your time (and that of your teacher as well) if you don't push yourself to prepare for them.
Set goals for sure. Find ways to measure them, find a couple more chances to perform than you are entirely comfortable with, and regardless to where you are in your career or ability, keep studying.
Now get back in the woodshed!