It can be difficult to stay motivated to exercise/work out. It takes a long time for it to become a real part of your routines and your lifestyle/way of life. Don't get discouraged. Even after decades of routinely having regimes, one can not be in the mood or feel motivated for a time. There are times when you just have to take a deep breath and force yourself through it. It also helps to break up your routines and the types of exercising that you do. I couldn't do any one or two types of workouts/exercising. I need a variety.
It's fun to learn something new like Yoga, a Martial Art, Pilates, Tai Chi or dozens of other activities. Think about something you have wanted to try. Sometimes, we need to try some new activities to find out which ones we like. Remember, it's just moving and burning up calories. There are a hundred ways to do this and many of them can be fun. If you don't feel like running, go for a long walk or a long bike ride.. I don't know your area, but a walk or ride to some shops, a cafe, a park, to a friend's house or whatever and that is always better than nothing and sitting around feeling badly that you are letting yourself down.
It also helps to maybe take a inexpensive class here and there. You'll be with people and can maybe find a few to connect with for more physical activities. Having a spouse or girlfriend or a buddy or relative or neighbor or co-worker, to do some things like play tennis with, golf with, go bowling, go bike riding with, walking with or whatever you like to do, can break up the monotony of working out alone and you can help to motivate one another and have some fun and share the experience. Heck, dancing is a great way to burn up calories and use all your muscles and meet people. You don't have to drink (calories lol) to go dancing and have a good time.
Break up your routines and add more variety to what kinds of exercising you are doing and it won't be so boring. Walk, run, swim, bike, play ball, work with weights, whatever. There are a lot of ways to burn off the calories and stay in shape. Try and find some company for some of your activities and try some inexpensive classes here and there.
Don't beat yourself up when you just don't feel like it. It's okay to skip a few workouts here and there, just don't let that become a habit. There are times when you just have to use your will power and make yourself do something, ........anything, will help. I concentrate on how much better I feel afterwards, how much more energy I'll have, more endurance, enjoy the endorphins, that I'll be less stressed out, sleep better and that I kept my commitment. That and the sooner I just buckle down and get it over with, then I can move on to something else I want to do. lol
Treat yourself afterwards to some rewards also, like a long soak, maybe a scoop of ice cream or something else that you like/enjoy. Feel empowered that you are doing the right thing and something that is for yourself, something that will hopefully benefit you for many years to come. Understand that there will be peaks and valleys along the way. That happens to everyone. Just don't give up, feel too down about it and just keep plugging. I think that the more you can mix it all up, have as many physical activities in your bag as possible and get a little company here and there for some of them, it would really help.
Sometimes, we need a change of scenery. If that means driving to a spot to walk or loading up the bike and doing the same thing, then do that. Change up your views and experience and even the time of day that you workout. Make it a little adventure. Don't set your goals too high either. Smaller goals are easier to achieve, build on and feel some accomplishment over, rather than goals that we feel we cannot stick with or make. Just keep setting them.
Look for some clubs/groups that get together. They usually have events/activities for all skill levels, whether it's hiking, walking, bike riding, rock climbing, bowling, archery, softball or whatever. Many charity events have physical activities to raise money and you can meet some terrific people too and for a worthwhile cause. Here, they even have clean the beaches or clean the parks days and people all get together and volunteer to to that.
Find ways to make the experience more positive for you to do, with a lot more variety, new activities, some companions here and there, changes of scenery and you'll be much more inclined to continue physical activities and be inspired to find even more new activities and goals. The more in person, face to face support you can get, the better.