Have you ever been so motivated to go to the gym for the first time that you commit yourself to working out everyday and working your hardest every single workout and as the days go by your motivation starts to fade a way and your start to go less and perform less at the gym.
That is totally normal! When you're a beginner it is okay to be a lot more excited than anyone that could be going to the gym longer than you have because when a person decide that they're going to do something different with there lifestyle it is given that this will give them a sense of change, challenge, achievement, and whatever drives them to do the thing that they want to do.
Now what you need to realize is that when you start feeling like you're losing the excitement you had from the very beginning, (this could be the pursuit of getting a healthier lifestyle, losing weight, gaining muscle, getting over a loss of a love one and so on). At the very root of this cause is for yourself to become better and start taking care of yourself a lot more, somewhere along your journey to start going to the gym has always been for you to become the person you've always think that you can be one day and that should be enough for you to think of whenever you feel like you have lost the consistency and excitement you once have, look at it from a different perspective whenever you feel worn down and look at the long road ahead of you.