The act of deliberately keeping yourself away from something is avoidance. Your avoidance of the outdoors this summer has left you very pale!
Some types of avoidance make a lot of sense, like the avoidance of horror movies by someone who's easily frightened. Others are less healthy, like your avoidance of doing homework, which inevitably leads to a panic when you realize it's all due tomorrow. In law, avoidance means "making something nullified or void," the way failing to fulfill certain obligations can result in avoidance of a signed contract.