QUOTE(elisabeth_rb @ Feb 21 2007, 09:14 PM)

Hmm, I was thinking of posting something similiar today. I have to keep reminding myself to keep my wrist straight. Is this something that will come with habit? Am I struggling with it owing to weakness or what? That is a definite possibility as I'm anything but strong.

One doesn't need to be Mr (or indeed Miss) Universe to hold and play a violin/viola. (Those on this forum who know me in person will testify that I am extremely petite. If I can hold a violin or viola, anyone can!!!). It's all about building the correct muscles in the correct way.
Human nature makes us lazy, we do things the easiest way possible even if that means the wrong way.
Correct posture will build the muscles in the right way, incorrect posture will not and will seriously debilitate your skills in the long run. This could be applied to any physical activity, not just playing the violin.
Stand up straight shoulders back, feet shoulder width apart. Don't lock the knees, let them relax a little. The major muscle areas required for playing the violin successfully are the shoulders and the deltoids (the latter are a group of muscles in the back region between the shoulder blades).
Flexibility of the left shoulder and wrist are also important, but this doesn't mean having to force things. Flexibility will increase with correct posture and regular practice.
Yes, it
WILL feel uncomfortable to start with, especially if you have been cheating and playing in the wrong way. Good habits and perseverance are the only answer I'm afraid.