NOTE: The SMART series of posts is best read from the first post. Start with Get SMART - Look yourself in the i - and read from there.
Attainably
This seems like the most obvious of the S.M.A.R.T.s so far - you mean that if I set a goal it has to be one that I can actually do? - DUH! On second thinking however this is a factor that deserves closer attention...