Not all of us have a ton of time, but I've found this exercise is quite efficient at building technique. It's appropriate for all levels, whether you're relatively new to the viola or you've been playing for years.
Keep in mind that quality is much more important than quantity here. If all you can manage is a few bars a day, stick to that at first. If you're not lazy, your hand will eventually adapt, believe it or not. Use a small amount of vibrato - just enough to keep the hand relaxed. Apply it consistently from start to end of each note. Get a nice, full sound with the bow. Don't be afraid to dig in.