vital part · (fig.) key point · crucial

Don't be afraid to invest time and energy.

Don't be afraid.

PARENTAL ADVISORY: If your children use TATOEBA to study languages, please take the time to search any choice words you wouldn't want them to read - and don't be shy! You won't believe some of the uncensored filth they allow on here, since they feel "language is language."

Don't be afraid!

His comment was concise and to the point.