You know you're not in the right frame of mind when you allow too many excuses to keep you from exercising. If you always come up with reasons why you can't get to the gym, take a walk, take the stairs or whatever else you're doing to improve your level of fitness, it's time to figure out why you are doing this to yourself.
Start out by looking at your fitness goals. You do have fitness goals, don't you?
If not, come up with some. Keep them realistic and allow for improvement over time. Depending on what you think will motivate you the most, you can base your goals on time spent exercising, goals for specific exercises, weight loss and so forth. You decide what will keep you going.
If you do have goals, why aren't you reaching for them? Did you set them too high? Too low? Too vague? Rethink your plans and figure out what you can do so that you really want to achieve them.
Now think about where you work out.
If it's at the gym, why aren't you going? Is a gym membership really the best thing for you? Can you make it easier to get yourself there? Would finding a friend or partner to meet there help?
If you work out at home, what's keeping you from doing it? Are there too many distractions? Not enough distractions when you work out? A television or radio where you work out can be a very good thing if it encourages you to use your equipment.
Or maybe you haven't bought any equipment yet. While a home gym isn't an absolute necessity, and many exercises can be done without equipment, it does make exercising easier. If budget is the problem, take a look at the possible solutions.
You can check garage sales for the things you want. Freecycle (a website where people offer things for free). eBay. You have loads of options that can help you find used home gym equipment in very good condition, and that can save you quite a bit of money over buying new.
Consider hiring a coach or personal trainer to at least get yourself started on a good routine. A professional can help you find ways to reach your goals and really motivate you to reach for it.
Despite all the excuses that are so easy to make, it is very realistic to plan to get fit in your spare time. It's just a matter of figuring out what will motivate you to keep working at it. Nothing good will happen otherwise.