We did a whole Torah-Tuesday class on this, all based on this saying from Zeide Moshe Rubin:

He used to say: Tea and Tehillim are always good, but they have to be hot!

Let me explain. In the old-times, no one ever drank ice-tea. So, tea had to be hot. And while a guest could decline food saying that they already ate before, but back in those days no one ever declined a cup of tea. No matter how much you already ate, a hot cup of tea was always good.

Tehillim are Psalms, the informal and unstructured prayerbook of the Jewish people, and other religions, too. Even if you already prayed, you can’t refuse saying a small chapter of Psalms for someone who is sick, or a problem that needs help.

But like tea, Tehillim needs to be hot, it ought to be said with warmth and feeling.