This is part of a comment made from a discussion on homeless people:
…It would be nice to think that I'm going to be able to help turn his life around but we'll have to see if he loses his steam or falls off the wagon.
What does lose steam mean? Since falling off the wagon means to resume drinking after having stopped. I'm guessing lose steam means something like to resume using harmful drugs after having stopped?
Best Answer
As @JohnLawler mentioned in comments, losing steam refers to losing energy.
In other words, energy, or capacity to work can dissipate and be lost.
Because of the disjunction, "or" instead of an "and" conjunction, this concern over the loss of energy may not relate directly to a loss of willpower that allows the subject to resume drinking; instead, it may refer to some other activity, like reliably showing up to work, or something else the narrator might have referred to earlier that was a condition of turning the subject's life around.