Common mental health disorders like anxiety and depression, are called common because everyone struggles from time to time.
We are all on a continuum.
We all have negative and anxious thoughts - whether this becomes a 'disorder' is just an issue of terminology. As a rule of thumb, if your thoughts and the way you have started to react, or manage, your thoughts (e.g. by staying in bed more, withdrawing from friends, feeling isolated, drinking or eating more, sleep problems) then its a sign therapy can help