I am quite a solitary person and spent five years virtually alone all week before the DH retired. I dreaded it but soon realised that being solitary can be a bit of a luxury.
Like you, I had the time without the money to make it amusing so I had to arrange my days with that in mind.
I had a regime where I did tasks in the morning:-housework, ironing, food preparation and baking, gardening, cleaning the cars and so on. I had paid for some of this to be done when I was working so it felt like my contribution to the domestic economy. I did not feel put-upon as I used the physical tasks as my fitness regime and listened to drama and other programmes on radio Four Extra while I worked.
The afternoons were mine to do as I liked. I always had a walk that lasted an hour at least and read my book. Reading is a luxury to me and I was able to read masses. At one point I used to visit the 'Silver Screen' showings of films at the local cinema. If you did not want to binge read you could watch a good film on TV, sew, pursue a handicraft, write letters, start a blog, do jigsaws, decorate a room.
Others often asked me what I 'did' and when I told them seemed to think I ought to be doing more. I think the 'more' was volunteering or going on holidays. I am sure that having a part time job or volunteering would ensure more contact with others.