In truth, Thich has described how suffering happens in the first place...
Believing tomorrow will be better, if it is not you will be let down immensely. This is the whole basis of all depression, things are not how you want, how you thought they'd be by now. These words are utterly poisonous because he is respected, yet he is causing more trouble for people.
Believing in this concept of tomorrow, striving to make it better than today, no matter what you do you will hit a wall, you will see you are fooling yourself.
"Sitting silently, the grass grows and spring comes by itself"
Nothing needs to be done, just go utterly into the now and there will be nothing else at all, you will not dream because you are already fulfilled. Of course, you will like his words, because they uphold your illusions, you have found something in Zen which upholds the worst aspect of Christianity.
Just be, here now.