Duhkha

Duḥkha , 'unease', “standing unstable,” commonly translated as “suffering”, “pain”, or “unhappiness”, is an important concept in Buddhism, Jainism and Hinduism. Its meaning depends on the context, and may refer more specifically to the “unsatisfactoriness” or “unease” of mundane life, not being at ease when driven by craving/grasping and ignorance. – Wikipedia

Duhkha is when you wish things were different. That wishing is the source of your unhappiness.

You see, it's now. It's always now. It's too late to change things. If you wanted things to be different now you should have made changes yesterday. By wishing things were different now you're wasting this now when you could be making changes in order to nudge the future in the direction you want.

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I feel like I said the same thing, but better, in it's always now.