When you observe your past actions, you may notice that your most productive moments are often generated by negative forces like fear (of losing an opportunity/of starvation/of someone else/of death), panic (the famous last minute productivity) or a sad life changing event. So, in general, you worked the hardest during the darkest moments of your life, for the simple reason that in these moments you often have no choice but to work your ass off.
But what happens when your goal isn't urgent?
Many people get stuck with their small goals like lose/gain weight, change a habit or a diet, start exercising or run a marathon... For example, I recently stopped smoking. I have to say I wasn't a huge smoker (2-3 cigarettes a day, sometimes more, and a lot more if I was partying) but still, smoking is smoking and in my head I knew it was temporary, "I'll stop one day" I thought "but not today". Another thing about me is that my mom is an Oncologist so I know all the ugly truth about cancer, but it's funny how it wasn't enough to make me stop: nothing was imminent so I always pushed it to later. Until I decided to stop for a different reason: I wanted to run faster.
Motivation with positivity
I read before about this positive approach that focuses on what are the potential positive outcomes if you change instead of the potential negative ones if you don't. Instead of thinking you want to lose/gain weight because you find yourself unhealthy/not beautiful enough at the moment, think of how healthy you will become and the confidence you will have. If you just started exercising and you compare yourself to others thinking you aren't fast enough/good enough and that's why you should work harder, it can be less motivating than if you think of how far you will go/how strong you can become compared to where you started (in general try to never compare yourself with others path, we come from different places and have different bodies/minds).
So when I finally stopped smoking, instead of thinking that I had to stop to not die some day, to not smell like cigarettes, to not age my skin too quickly etc... Well I started thinking the other way; this time it was to be able to sprint faster at Barry's Bootcamp as I already made progresses but felt like I would feel so much stronger if I stopped... And I was right! After 2 weeks without touching a cigarette, I already could sprint 0.5 mph more than before! I also wanted to feel healthier in my everyday life and keep my money for better things. And because of that, the few moments when I craved like a cigarette it was so much easier than before to make the right decision.
It's subtle because sometimes it's just turning a sentence the other way ("I will have a better skin if I change" instead of "I have to change because my skin is/will be bad" which is technically the same thing but it rings a different bell in your mind) but more than the saying it's the positive thinking and how you see the situation. I don't know if that will work for you, but I know it works for me because I am tired to always think of the bad things that can happen to me as a motivation force. I just want to be surrounded by more positivity in general in my life.
Thinking positively doesn't mean closing your eyes
Of course, you also have to face the negative things in life because nothing good comes from closing your eyes to the truth. As another example is how I decided to eat vegan and what made me change -the horrible videos and the truth about climate change opened my eyes- but it doesn't have to be your motivation force! Because in the end what made me really go vegan is all the delicious meals I tried and how I felt healthier and how my skin got better (I already had good skin but some friends told me the last 2 years my pores went smaller which is when I started a plant based diet). So, maybe in the end it's a mix of both: be clear about your situation, but use all the positive things that can happen to you as a motivation.