The main way to tackle this would be to look at the cause of your anxiety
. Anxiety is always about fear and hence you need to know what is the fear about. Also you say you have this only when your daughter is away but also say that you are constantly worrying. If both of these are true, then that means you are having what we call "anticipatory anxiety" i.e you are worried thinking about the anxiety you are going to have once you are alone.
Behavioural activation...i.e keeping yourself busy with lot of activity is one of the best self help methods that helps depressed people but here your problem appears to be mainly worry/anxiety.
I would suggest that you follow the recommendations in the above two replies,if your problems are not too severe/not having much effect on your social/family/occupational life and you are not too distressed. Yoga/meditation
might also help.
But if the severity is high/its affecting your life too much/if you are too distressed, please contact a psychiatrist
for appropriate assessment and treatment.