1. Your second career will be a business. Run it it like one.
2. With some exceptions, most professionals don’t know what they don’t know about running a business. My Dad called this “compound ignorance”. I know you feel you should know everything about everything because that’s the way you were trained. Just relax into not knowing everything. Find people who know what you don’t. Your second career is less likely to crash and burn.
3. Reflect on what skills, competences and passions you have not yet fully exploited in your career because you couldn’t, for whatever reason. I call this your “A Asset”. Don’t be put off by people saying “you can’t”. As we say where I come from, “feck the begrudgers”. Go for it.