Freshly brewed from on high Ecclesiastes perks me up when I'm feeling low and wakes me up when I'm backsliding.
Personally, I love Ecclessiastes' bitter taste, its downright cynicism, its in your face pessimism. It is guaranteed to make your mood gloomy or at least introspective with its harsh overdose of brutal honesty served hot straight from old Solomon's kettle.
I'm sure other Christians could relate to this special book in this way, even if they literally hate coffee. Realty bites and this book serves no lesser purpose than to serve reality as it is.