Strength of will
Track progress
There are studies that prove that tracking progress in achieving goals improves well-being and increases happiness. Evaluating your results, you will see that you are going in the right direction. All this in the end will give more motivation.
When you fall, get up
In pursuit of the goal, you will fall more than once (so we say "when", not "if"). It is important to be mentally prepared for the fact that there will be defeats.
You can also lag behind your plan for various reasons: illness, other cases, difficult circumstances. Do not give up - go back to work as soon as you can. Do not let the misfortunes distract you from the goal.