My answer to this question has evolved a fait bit over time, and probably will in the future, but at the moment I find that making sure that I deliver at least one item (however small) every week helps; I feel I am always making progress. So if you have big projects, break it down into simple, manageable steps & tasks. Then work your way down the list.
Completely agree with @cgsmith.
I did an internship at age 30: it was 2008, the economy was in the doldrums, and I was desperate to change the direction of my career. The internship lasted 6 months, I was obviously far more experienced (in terms of strategic thinking & organisational experience) than other interns, my boss and even the boss of my boss. Long story short, 6 months later I was hired by the company with a decent position, salary, and having completed my professional turnaround.
Edit: this bizarre story has been picked by other news outlets, so maybe there's something to it.
https://www.theguardian.com/technology/2017/nov/07/facebook-...
http://www.zerohedge.com/news/2017-11-06/facebook-now-wants-...