Believe it or not one of my favorite household items to use is my toothbrush. I know what you're thinking "how the hell can you workout with a toothbrush, it weighs nothing." I use it mainly for working my fingers and my grip by rolling my fingers until I get a full grip on the brush and hold for a few seconds then do a couple more more reps that way. Be sure to do both hands, it develops dexterity and isometric strength from the squeeze you're putting on. I don't recommend toilet paper as a workout tool but that's up to you, a smooth rounded hairbrush can work the same way or you can do push-ups on your bathroom sink; it's like a modified version of dips but to get the best benefit, tense your muscles as you go up and down, works the chest, abs, arms and shoulders.
A good number of houses have stairs depending on the level of the house itself. With stairs you can do a variety of things that won't cost you anything; step-ups, jumps, push-ups, duck walks, dips, you can even have someone hold your legs as you walk up and down the stairs on your hands. Be simple and creative, use your imagination. During my MovNat or Darebee Workouts I use the stairs of my house for quality jumping, stepping and Push-ups at an elevated level to challenge my body in a different way. Even if all you can do is walk up the stairs barely that's great, one thing I like to do especially if I want to strengthen my joints is after a couple steps, press your feet into the ground for an isometric contraction using an "sssss" sound as you exhale. Do double steps as you walk up go sideways to strengthen the hips and gain flexibility in your hip flexors and extensors. Many ways to use the stairs.
Where is one of the best places to be after a long day at work and want to chill out? Most likely your couch or comfy chair. Now you can still get an awesome workout even in the comfort of your favorite place to sit. Want an example of what you can do even if you just want to sit and exercise....Get yourself Sofa Abs or Get fit watching your favorite movie and why not kick back and do a little workout during the commercials of your favorite TV Show. Don't make excuses, make the time to exercise in your home and get in great shape.