I am one of the lucky ones who have this luxury every day! I adore reading,(REAL books with pages!)or researching my favourite subjects on-line.I also spend a lot of time in my garden enjoying the plants,Green Frogs and huge tropical butterflies. I love living alone,as I do not feel I am neglecting anyone when I decide I want to do these selfish pursuits,and others such as enjoying a long luxurious bathe,or listening to the music I like best. And the greatest one of all is that I can lie on my bed surrounded by my beloved dogs without the judgement of anyone else who does not think this is a healthy practice!!
Might be the most boring obvious answer but i read a book if i ever do find myself alone. Sometimes I wake up really early and I go for a swim or go to the nearest park for a walk. But the ideal would be creating something beautiful and decorating my place! and if I don't have the energy I would day dream for hours!
Do mean as if there was no on else on earth, or just no one to hang out with? If it were the latter, I'd just spend most of the day on the computer, reading, etc. If it was the former, I'd probably wonder round the deserted streets, seeing what it felt like for it to be completely empty.
I'd be lazy and indulgent. I'd have a bath in peace, read a book and catch up on some zzzzz's. I'm on the go every day so this would be a great recharge for me. When I've recharged, maybe a walk on the beach.
sit down and have a nice hot cup of tea and then decide to do one thing for myself. If its not raining that might mean a walk into town to the art gallery. I don't do it often enough and its there everyday, I just don't get there.