Answer:
Internal pressure has to deal with how one views themselves, or how they believe others view them. Taking this into account, reasons such as stress, feeling low about ones self, seeing a change (whether good or bad) to come out of taking drugs or simply being unhappy in life are all things that can lead someone to abuse a substance, legal or otherwise.
Step-by-step explanation:
It's hard to decipher why anyone does any sort of driving action. Especially one that can be as harmful as taking strange substances. In this case, the way someone's outlook on life is, or the way they perceive themselves can be really strong persuasions to want to try or continue to abuse any given substance.