Apologies if anyone has suggested these strategies for countering negativity already.
Biscuitmuncher It seems as if you are dwelling on things that make you unhappy. You could try to counter this by listing things that make you happy. I would advise, if you don't have mobility problems:
* that you go outside at least once a day, preferably in the morning and look at the sky (don't look directly at the sun)
* for each of the sad things you listed in your post, think of and write down something that makes you happy. You might get a pretty notebook, diary or pad to record things. You may think there's nothing but these things might be small e.g. birds singing (some e.g. robins do sing in the winter) If you put food out for the birds they will come and you can watch them. Better still, put water out and you can watch them bathing (hilarious) or wallowing (pigeons).
* Write a list of your sad things. Last thing at night, put that list in a drawer (not in your bedside drawer) and tell yourself you will look at the list tomorrow. Eventually you might forget to look at it! Take your happy list with you everywhere, look at it often, update it regularly.
These things won't take the sad things away but will distract you from dwelling on them.
* Search Google for reasons to be cheerful
Here's a list of some of the things that make me happy:
Watching the birds
A sunny day
A cloudy day - spot shapes in clouds
Going outside in the rain (I have several umbrellas)and
Photos of my family
My hobbies (sewing, karate)for
My first coffee of the day
Video chatting with my daughter
My two lovely sons
My lovely dog