When a word has a negative connotation, that means that is suggests something bad. For instance, exploit suggests something bad while employ suggests something good. Infamous: Negative Infamous means popular from a bad deed.
Astute: Positive Astute means smart or good at understanding people
Secure: Positive Secure means safe. We normally pair "safe" with a sense of comfort.
Difficult: Negative Difficult means hard, and most of the time people don't enjoy doing hard things.
Freedom: Positive Freedom is the ability to do anything one desires without restraint.
Childish: Negative To be childish is to be described as immature or to act lower than one's actual age.
Frivolous: Negative Frivolous means to be useless. As humans, we always want to feel important or loved. The opposite would be to feel useless.
Reluctantly: Negative To do something reluctantly is to do something not out of one's personal pleasure. This normally requires coaxing and typically does not promise rewards.
