Loss of motivation? Motivation is the product of the desirability of being at the imagined target and the feasibility of reaching it. If both are high then there is usually little problem with dedication.
Been there, as a little kid I wanted to become fighter pilot but when I started to realize the required dedication and the many booby traps during the training I switched to physics, loss of (feasibility) motivation. The new (end state) motivation was wanting to be a part in the solution of the impending energy crises with nuclear techniques etc. And that was around 1970! (Club of Rome), what else is new?
But in due course I had a severe crisis with motivation, since the boys dream refused to go away. The end state fighter pilot seemed a lot more attractive than physicist, moreover the accumulating tension of the cold war with the red danger a mere few hundred miles away, required us to not sit idle and do something, that added certainly to its motivation and all of a sudden the long and hazardous training course did not deter that much anymore. It was enough to apply succesfully for the selection and complete the education.
So perhaps it's about wondering if the desired end state is still desirable and if the way to get there is still feasible.
