I want to take action and not continue to sit on the sidelines but would like to hear from others that might have been in similar situations in the past.  

@Tomas Lam, in order to have something actionable I think you would first need to show a "loss".

Cash for keys works pretty well too and may be your easiest choice of action.

But I am still happy because it was progress, and it forced me to take action and it was such a great learning experience!

My advice centers around one word: action.

Ask yourself how you would like to hear the news that your rent/mortgage/taxes were being doubled.  

Doesn't mean they won't do so as time progresses but it is 100% time to start legal action. 

I began the year with a ton of action, including the following highlights: Joining a mastermind group and hired a coach Read nearly every multi-family book I could get my hands on Attended several Multi-family oriented conferences (3 to date, a couple more booked for the year) Networked at every chance including connections on bigger pockets, local meetup groups, mastermind connections, and linked in connections where it seemed mutually beneficial Started a podcast which officially launched in March (now recording our 20th episode this week!)

@Andrew SimmsMASSIVE ACTION

My options are A) accept the stability and lesser headache that comes with taking no action for the time being in exchange for accepting his below-market rent, or B) accept a turnover from a good tenant and pay for a renovation in exchange for a significant rent increase (in the ballpark of +15% right now with a strong upward trend).My inclination is to go with option A and renovate when the tenant chooses to leave or when the disparity between what he pays and what the market rate is gets closer to 25%.