Depends what people.

Your boss, your wife, your parents, your family? It does matter what they think.

You shouldn't bow to their every whim, or let their opinions decide what you'll do every time, but pissing off those people or losing their respect will definitely have an impact on your life.

And winning their respect and admiration will definitely have a positive impact on your self esteem, family life and possibly finances, all of which correlate with good mental health.