It might be a similar feeling to getting a burst of energy late at night, right before bed time. Feeling like you're now ready to work on that project, but alas, you need to get up in the morning, so it will have to wait until another day.

The truth is, you weren't going to do that thing anyway. That burst of energy is an illusion. It's a defence mechanism to make you feel like you would be an extremely productive person if it weren't for your obligations. In my experience, if you take away the obligations from that scenario, the burst of energy disappears.