Sometimes people who are living on their own for the first time don't take good care of themselves. Explain why.

This person may not have full awareness to their needs and desires in a given environment. Humans take influence from others so with respect to the fact that we may be capable of being self-sufficient, some may depend on outside influences rather than solely taking guidance under intuition. It’s all a matter of adaption to the given circumstances that people are placed in. Living on your own takes adjustment to such change.

It’s very stressful, and something new . you have to start the “grown up” life where bills and food is on you now, not mom or dad

In this sentence, hard is the adverb because it is modifying the verb.