The ideal logo will convey 1) Motivation and 2) Mafia. It's a fun/sexy/dangerous blend of positivity and inspiration with guns and intimidation.
Check out the mafia photo shoot we did here: http://curiousjordy.zenfolio.com/goalmafia
In terms of time period, the vibe is more modern mafia (think 1970s Godfather to the present, Goodfellas, Casino, Sopranos). (as opposed to roaring 20s or 50s mobster)
Note that the emphasis is on "fun" or cartoony threats, as opposed to photo realistic blood spatters, for example.
We have a bunch of reference material to help you get inspired. You can see our current logo at http://www.goalmafia.com, along with a mafia-style photo shoot we did, some customer testimonials, etc.
Currently the site features a dark color scheme - blacks, yellows, red, and white. It would probably make sense to stick with this general theme.
Some reference images including our current logo are attached.
Logo should be a standalone image against a transparent background.
Have fun with this!!