My first big girl job

How can I be almost 52 and I feel like I finally have my first REAL big girl job? And I’m scared shitless.  Scared to fail, scared to let others down, scared to let myself down.  Scared to succeed, scared to do well, scared to like it.  Scared to immerse myself and lose myself in another job.  Is it a job or a career?  What was my last 32 years in the working world?  A job or a career?  What do I want this one to be?  What will this one be?  Do I make that choice?  

I am trying to keep my mind open to anything that comes along in my new big girl job. I don’t want this job to define me. I want to define the job I am doing. Does that make sense?