So, if you spend 2 minutes trying to research how to get motivated, you will quickly come across people saying that you can’t rely on motivation, you have to be disciplined. And I guess that’s true, but I don’t think that this means you shouldn’t try and be motivated. Discipline, means you go for a run when you had planned to, never-mind that your day at work was more tiring than usual, or the commute took longer, you just go. Motivation, means you have a reason to go running when it’s cold, wet, too hot, you’re too tired. It also means you have a long term goal and you use that too balance everything. If making yourself go for a run today would be damaging to your goal or to your health (physical or mental), then go tomorrow.
So be disciplined, but use your motivation.