If you run regularly, your stamina improves.
Running regularly improves your stamina.
She spent many years working in the hotel industry, and two years ago, she decided to return to full-time study.
Having spent many years working in the hotel industry, she decided to return to full-time study two years ago.
As an intern I was given menial tasks with limited responsibility, which I absolutely despised.
I absolutely despised being given menial tasks with limited responsibility just because I was an intern.