Same here :) I get bored quickly when I have learned all I need to do a job well...that's why I was constantly changing my roles in my last company and when there was not much to build up (I was at a startup) I left. I am now quite happy in the middle - part-time job that I love and growing my business on the side. I too find it hard to switch off my brain and take rest days and the part time job helps me to keep my sanity because I know the rent is safe and I don't need to press the panic button everytime business is going slow.