If you are talking about physical endurance, the U.S. Army has a number of biodata items it refers to as "fitness motivation". They also have a self-efficacy scale, but they do not have SE for endurance.
There are scales of self-efficacy for task persistence, but mainly applied to academic environments. Here's something interesting regarding pain management, which may be more related to physical endurance than "academic endurance."
Probably some of the best work is that carried out by Kellmann, M., & Kallus, and their RESTQ Sport Questionnaire. It has been used extensively in rowing as well as some other endurance sports.
We have used it with The National Lightweight Women's team with incredible reliability, especially as regards making weight and race preparation and readiness.