Just doing the right stuff which utilizes 100% of your skillset and pushing you to expand it further. 
I'd recommend you to read this book. 
https://www.amazon.com/Drive-Surprising-Truth-About-Motivates/dp/1594484805?ref=d6k_applink_bb_dls&dplnkId=eb7392d1-48fe-4df7-9194-7a14400db874