Mental strenght is a lot like phisical strenght
If you wanted to be physically strong,
you'd need to go to the gym and lift weights.
But if you really wanted to see results,
you'd also have to give up eating junk food.
Mental strenght is the same.
If you want to be mentally strong ,
you need good habits like practicing gratitude.
But you also have to give up bad habits, like resenting somebody else's success.
No matter how often that happens,it will hold you back.