What do you tell yourself when you want to skip something, a mantra of motivation to keep doing it, even when you don’t feel like doing it or are stressed, etc.?

I have my favourite show and the show cast is a very strong team and they have a lot of problem but they still doing their job and they are "happy".
So they give me motivation.

Kažem sebi da je to za moje dobro, moje blagostanje. Da radeći to idem ka svojim ciljevima i da se ponašajući tako, ponašam u skaldu sa svojim vrijednostima.
Ukoliko, odostajem od onog što bih trebala raditi, podsjetim se da tako napuštam sebe, svoje želje i čak nepotrebno odgađam njihovo ostvarivanje.
Kada sam anksiozna, razmišljam šta je to što ja mogu uraditi, što je do mene i tada odgodim brigu, ondnosno razmišljam u koracima. Planiram jednu po jednu stvar i tako odražavam motivaciju, koncentraciju i smanjujem nelagosnost koja mi se napočetku javila zbog brige i neizvjesnosti.

Everytime i do something tiring like school work or even excersice i tell myself if i do it properly now it will be easier next time

I usually use the good old excuse of “I deserve a rest” when I don’t feel like doing anything. A mantra to push myself to do something would be “Just start and it’s done” because I know that I am the type of person to finish what I started. Consistency and commitment is something I have been working on for so long. Reaching these goals would definitely boost my confidence and I believe making myself better is making the world better.

Sometimes I just don't push myself and just skip. I believe that it not have to be always good to do things when you don't feel like it. But I am trying to keep on mind that I am fighting a battle. A long one. And my future myself will thank me if I am going to complete this now.