Here are some ways to to start without any equipment.
1. Walking/Jogging
It's always great to get out and enjoy the scenery and fresh air, but rainy days are always a concern. Consider these ideas - If you've got stairs at the house, try going up and down them for 15 minutes. This will tone up your legs and buttocks while getting some light impact cardio aerobic work as a bonus. No stairs? jog in place - It's good for improving heart health. You can even do it while catching your regular TV shows or listening to your favorite tunes. This would require some decent shoes to help reduce stress on your joints, but otherwise no equipment is needed.
2. Free Squat
This is great for for your legs and buttocks. If you have difficulty balancing, try squatting with a foot stool to keep from toppling backward or try holding your arms in front of you for maintaining balance.
3. Jumping Jacks
This should be fun because most of us did these during school or as kids having fun.
More importantly, a few hundred of these will surely make your heart and lungs work. They can be used as a warmup, or they can be done as active rest between sets of squats.
4. Pushups
The pushup a great upper body exercise that uses the shoulders, chest, and triceps muscles. These may be tough for you to do, so if needed you can try them on your knees rather than full push ups. As you get stronger then use full push ups.
5. Ab Crunches
Ab crunches are excellent to tone your core. Ab crunches are a better choice than sit ups because they cause less stress on your back. Do not pull forward on your neck, instead cross your arms over your chest or just keep your hands resting very lightly on the head.
Consider these suggestions about getting in an improved workout routine at your house with only minimal cost or room required, there are 2 ideas you should consider...
Jumping Rope
Costing under 20 bucks, this is a deal. You'll get tough cardio workout in only about 10 min.
Adjusting Dumbbells
These can run anywhere from 25 dollars for some used, all the way to $250 for some the more higher end dumbbells. The range of exercises you can do with a set of these is truly unlimited, yet they take up virtually no space.