[moviewise]

I'd argue that the problem when you don't feel motivated (provided it's not because of a lack of sleep, hydration, or nutrition that's making you feel tired) is that you are not learning something new. This is why it's important to vary the location, or time, or who you go hiking with etc. If you add some variety to your activity, you will feel more motivated because you'll get to learn/experience something new, which is intrinsically exciting and rewarding.