If you've recently been initiated into the Vim users cult and, like me, you also don't like leaving your terminal that much anymore, you're probably being forced to do so whenever you want to do stuff like previewing your markdown documents. Sweat no more;
glow got you covered.
brew install glow.
Markdown: This is a command line tool for converting your MD files to HTML
Lynx: A terminal-based web browser for rendering HTML pages.
brew install lynx markdown
Convert your MD file to HTML with markdown and pipe the output to Lynx
markdown MyWonderfulDoc.md | lynx -stdin