To forget to thank may be wrong, but to refuse to ask is a thousand times more harmful. This psalmist will not make that mistake: he has learned from experience. The happiness and peace he knows are enduring and fulfilling. He has found his comfort zone in the Lord. Despite his trials and struggles, he is at peace with himself and God. Few understand this: the celebrations of harvest time seem to satisfy others. There is no harm in these things—they are gifts from God, and we enjoy them gratefully. Our mistake is thinking they can bring lasting satisfaction. To be at peace with God is to be at peace with oneself.
Trust and even joy are possible amid trials (cf. 2 Cor 7:4; Gal 5:22; 1 Thes 1:6). Jesus, in Matthew 5:22-26, tells us to reconcile quickly if we become angry to avoid unwanted consequences.
Like the psalmist, if we want to sleep peacefully at night, we should not carry our anger into bed with us.