This blog post by Lynda Bourne makes several clear and simple points about a critical success factor for projects and people. She combines the concepts of persistence and resilience. (I have got to start doing that and making up words!)
Angela Lee Duckworth writes and speaks about 'Grit.' She's inspired a chapter in my own next book on the subject of 'Grit' - a combination of behaviours that amount to not giving up and overcoming obstacles and set-backs. Tenacious, dogged, perseverance. Grit, it seems, is the number one attribute that leads to success at whatever it is you're wanting to be successful at, be it Olympic gold medals, corporate success or mastering violin concertos. More importantly, this thing called Grit isn't something you're born with or without, like height. It's something you can choose to learn. If you want. If you really really want. Here's a link to Angela's TED talk on Grit and how to go about learning it.
Intelligence is handy but the research shows that Grit is what sets the winners from the mere participants.