NU says computer health is always LOW

I am running Norton Utilities version 16.0.2.28 on Windows 7 Pro 64.  NU always indicates LOW computer health.  I have run all the tools that I can (and have 'repaired' all that was indicated).  The only thing that I have not done was to run defrag on my system drive which is a solid-state drive.  When I try to defrag this drive NU says that it is not recommended since it would shorten the life of the solid-state drive.  What next?