All animals need exercise and most rabbits will not get enough exercise just sitting in their cage all day. However, it can be dangerous to let them roam around. Some rabbits owners will invest in a particular made day enclosure where their pet can roam around safely and enjoy exploring its environment.
For a lot less you can walk your rabbit with a harness in a safe area. Harness are made from soft leather or suede so they do not pinch the animal or are too heavy. However, this means they are lightweight and can be easily chewed. Never leave a harness on your pet rabbit and it will not chew it off. As well, it may become trapped and hurt itself.
The safest and cheapest method of exercising your rabbit is to let it hop around an area in your house. If you are not comfortable with it being on the carpet, only allow it access to tiled or hard floors.
Watch out for wires lying around that can be chewed. Wrap any loose wires or cords in aluminum foil to stop them from becoming lunch. You could even spread something on it that the animal would not like to eat, like mild chilly paste or chest rub. Watch this does not rub off and stain your furnishings.
Rabbit Agility is a new sport that is coming out of Sweden. It is the same as dog agility only the equipment is much smaller (of course) and the rabbits run the course on a harness. It looks like a lot of fun and is great exercise so if you're interested why not investigate having a go yourself. You could build some simple jumps, ramps and poles for weaving in your backyard out of pieces of scrap.
Exercise balls are a new popular toy for smaller pets. You simply put the animal in the ball and allow it to roll around your house. Do not leave any animal in one of these for very long. They get hot and without access to water, your pet could soon get sick and die. They also upset the animal's equilibrium and can make it dizzy and sick.
Rabbits in particular are curious creatures and need the stimulation of new experiences. Large colorful cat balls with rattles are good. Balloons are cheap and rabbits love nudging them around the room. Pine cones are another favorite toy. As well, you can give your rabbit whole apples that they would enjoy rolling around and nibbling on. Hang carrots, celery or milk thistles from the top of the cage to encourage your pet to jump up. By using your imagination, you can use your rabbits food to provide physical and mental stimulation.
I hang cat toys, such as rattle balls, from the tops of cages to encourage the rabbits to lift up and investigate them. This means that they are exercising to and being given stimulation.
Cat toys are made of tough plastic and will last much longer than cheaper toys. You will have to make sure your rabbit does not chew on toys and bite pieces off. You will not want it digesting pieces of plastic and becoming ill. Do not purchase toys that have paint or loose parts that could be swallowed either.