I agree with others Sheena that your world is not going to suddenly become exciting and fulfilled just because you think it is boring and humdrum.
Others can make suggestions about what they do with their time, what makes them forget boredom and find that the time has flashed past while they were doing something, but who do you think is going to change things except you? No-one! You need input into your brain to have something to talk about. No-one can put it in there except you.
If you have never been one for hobbies, you don't have a store of things to occupy your body and mind, and now you feel the need for them. You need to take stock and plan what you will do, particularly as winter is coming on, and walking the dogs becomes less fun.
You need:-
1) Something physical - buy a pedometer and try to work up your dog walks, aiming for 10,000 steps a day. you will find that physical exercise makes you feel more cheerful (if rather exhausted) Don't always go the same route, vary it, and keep a lookout for things to tell DH about when you get back. Better still, join him in his walks and talk as you go. Ask him about his interests, his butterflies and conservation.
Start an interest in something you pass on these walks - wild flower identification, the history of the places you walk through, anything at all. To start with it may be an artificial interest, but as you find things out, it could become absorbing - and you would have another subject for conversation.
2) Something mental - you obviously have a computer. What do you use it for? There are many ways to use a computer which stimulate the brain, and you don't need to know anything about the inside of it.
Do you know anything about your parents, grandparents, greatgrandparents? You could research them and have your own Who Do You think You Are.
There are sites which offer free courses in all kinds of things. There is Gransnet, which could fill in your entire day with chatting and reading what everyone else is doing, if you let it.
Offline, there are local authority day and evening courses in many subjects, some hard work, some lighthearted, all of them interesting. They start in most places very soon, so get online and look for your local area adult education classes. That will take you out of the house for an hour or two weekly for 8 or 10 weeks, either during the day or in the evening. If you qualify for concessions, it will cost you about £20 for the whole course.
3) Something creative Do you knit, crochet, sew, paint, do mosaics, woodwork, anything at all? If you do, get going on a project for the winter. If you don't, look again at those LA courses and find something that takes your fancy.
4) Something for others If you are lucky enough to have reasonable health and enough money yo live on, think of those who do not, and help out a charity. Charity shops are the first thought, but there are other ways to help. Your local authority website probably has a list of local charities. Just about every one of them is desperate for volunteers.
If you can do three out of four of these headings, you will find that DH is pleading with you to stay home and talk to him. Be nice and tell him all about your busy life over the cup of coffee he makes for you.