That's a shame. I've done the opposite recently and moved from a 'corporate' job into co-founding a start-up. Without the fear of making payroll each month, I know now why it's easy to rest on your laurels and become a clock watcher.

My advice would be to start something up again on the side. Remember why you loved the autonomy of the start-up in the first place and transition yourself back towards a self-sustaining lifestyle.

If nothing else, the thought of working on your 'real' venture will get you through the day at work.