- Some patients with severe headache problems become habituated to ergotamines and other non-narcotic drugs.
- Un-learning is more difficult than learning - because we become habituated to thinking or feeling in certain ways over time.
habituateha‧bit‧u‧ate /həˈbɪtʃueɪt/ verb 
be/become habituated to (doing) something formal to be used to something or gradually become used to it: 
Over the centuries, these animals have become habituated to living in a dry environment.
be/become habituated to (doing) something formal to be used to something or gradually become used to it: Over the centuries, these animals have become habituated to living in a dry environment.