Your helmet and goggles are a good investment in your safety. You want to keep them in tip-top shape. As they will be the only protection between your head and the ground in case of an accident.
No matter what the brand name is or how much you paid for it, a helmet will age. The resins and foams that make up the helmets, although many are made from space age polymers, will degrade with time. If your foam isn't as cushy as it once was, your head isn't as protected. Look into replacing your helmet before your next ride.
Also, another mistake people make is how they store their helmets. Don't hang your helmet off your ATV or motocross bike. This can stretch your chinstrap and an ill-fitting helmet isn't safe. Another reason not to hang your helmet off your ATV or bike is that gasoline fumes can break down resins if your helmet is exposed to it on a daily basis. If you store your helmet in a garage, make sure it is not near a can of gasoline.
If your helmet has fallen from a distance of 4 feet or more and that includes the time it just rolled off the kitchen table, you should probably look into replacing your helmet. Helmets are good for one impact only - inspect your helmet for small and tiny fractures in the surface. This would indicate that your helmet has been used in an accident or dropped from a significant height. In either case, the protection qualities of the helmet have been compromised and it isn't safe for you to rely on for your protection.
Goggles are another item you'll want to take good care of. They do a good job of protection your eyes and shielding them from flying rocks and debris. Over time your goggles will get small scratches in them from doing their jobs and this will make your visibility less than 100%. A quick fix for the scratches is to use a soft clean cloth, like an auto detailing cloth that has no fuzz or lint - a microfiber towel would be best, and spread some Pledge (the furniture product) treatment on the lens, use a small bit at a time and rub off the excess. The little scratches on your goggles will be filled.
Keeping your helmet and goggles maintained will save you money in the long run because you won't have to keep replacing them. Also, you'll enjoy a safer ride knowing that you're fully protected!