Started a successful company but was young/inexperienced in running something of that size, so I delegated too little and wanted to keep track of everything myself. The company grew (too) quickly and I was stressed out all the time, working 14-16 hours on things I never should have (hindsight) been working on. I was already burnt out I think but one day my body halted this as I had mild stroke; I recovered physically quite fast but mentally the burn out took years working part time to fix. Luckily there were profits and dividends to be able to do that and take my time. I do business very differently now and never felt anything close to the stress I felt at that time again.