gpg is a powerful encryption tool and can do many useful things, but
sometimes you just need a simple tool to encrypt and decrypt data
for yourself.
Start with the following alias (in .zshrc or .bashrc, depending on your shell - change to gpg2 if you use gpg2):
alias gpg='gpg --default-recipient-self'
This alias makes the default recipient be you, so if you don't specify one, it will be encrypted for you.
Then to encrypt a file:
gpg -e FILE
And to decrypt it:
gpg -d FILE.gpg -o FILE