Each little glimpse of equanimity and saying yes to life has the result of "positively conditioning" the mind, just a little, which makes it that much easier to remember in the midst of tough nanas and depression and obsessive thoughts. We can usually endure any difficulty if we know the difficulty is temporary and that veil will eventually be lifted again.
No one ever just develops in a straight line, getting better and better... It's much more scatter shot, all over the place. it's actually more like watching someone do an oil painting: a splash of color here, a different color there, little dots all over the canvas, for hours and hours, and then amazingly this big spacious picture starts taking form, almost as real as a photograph. Amazing.
Each time you objectively and fully experience a sensation, an urge, an emotion, or thought pattern, it's like you have separated a muddy mess of oil paint into the bright colors that make it up. And your life becomes a little more bright and colorful. Not all at once, and the colors can get mixed up again, but we develop this instinct that things can be bright and colorful.
Ironically, once you go looking for the bright and colorful --- saying yes to life --- you see more and more bright colors. That's why after a while it isn't a total uphill battle. The mind wants to mindful and joyful and equanimous and cool as cucumber

So we will always get pulled in that direction, it just takes time.
It's important to know that when the "bad stuff" shows up in our sits, it's just our mind working on taking a muddy mess and turing it into the bright colors that make up that mixture. We need to see the bad stuff so that it can be transformed into the good stuff. And the way it gets transformed is with patience, acceptance, and curiosity.