You build inner strength through embracing the totality of your experience, both the delightful parts and the difficult parts. Embracing the totality of your experience is one definition of having loving-kindness for yourself.
Loving-kindness for yourself does not mean making sure you’re feeling good all the time—trying to set up your life so that you’re comfortable every moment. Rather, it means setting up your life so that you have time for meditation and self-reflection, for kindhearted, compassionate self-honesty.
In this way you become more attuned to seeing when you’re biting the hook, when you’re getting caught in the undertow of emotions, when you’re grasping and when you’re letting go. This is the way you become a true friend to yourself just as you are, with both your laziness and your bravery. There is no step more important than this. Pema Chödrön