1. Save up as much money as reasonable. This will help buffer you in case you lose your future job (and can not return to your old job).
2. Retain as much of a good relationship with your current employer as possible...Because if you lose any other jobs, you want a fallback. This might seem odd, but when i worked in real estate, apparently that was somewhat not odd. Folks jumped ship from one realtor company to another and after some time back again, etc. Not everyone, and not all the time, but this industry more than others that i've worked in seemed to be ok with this. (I'm not suggesting that you joina real esate company, simply that some industries are ok with same person jumping back and forth into a company.) Also, if you hit a really hard time and have dependents and/or need any benefits like healthcare that come with this, existing job...you want to be able to return to your legacy job in a pinch and provide for your family, etc.
3. Once you have some savings, and a good relationship with soon-to-be-former employer, try one of the following: join a startup, and maybe join it at a slightly junior level than what you do currently; or, start looking at contract-related/project-related work; or, try and start your own business (I suggest a 1-person business at first...do not go for some mega business or even a multi-person company right away). In other words, do NOT try to get a "conventional" full-time/permanent, 40-hour per week sort of role at a non-startup firm. Any of these options will expose you to very different scenarios...and all could be something that you either try for a short time and then move onto other jobs...Or, if you enjoy, can stick to the same one.
I want to clarify again, that doing the above is risky...or at least, if i were in your frame of mind (as you described), it would feel very risky to me. And even if you can mitigate the risk at first, you might still feel overwhelmed since even only the "newness" might open up new/rusty synapses in your brain...likely giving you that nervous though maybe exhilarating feeling. FINAL CAUTION: I am not a doctor nor life coach or anything like that...I am only a random person/outside observer on the internet, so please take my suggestion with a grain of salt for what is appropriate for your life. Good luck!!!!