Would you like to feel happier, more motivated, and better able to tackle your most important tasks? A small addition to your nightly routine that's backed by brain science can help you do all of that. I've been doing it myself for the last couple of years. It's made a big difference for me, and it will for you too.

All you need is a pencil or pen and some paper, a notebook, or a journal. You could use your phone or tablet instead, but keep in mind that most sleep experts agree that you should avoid electronics right before bedtime. The whole routine takes between three and five minutes.

1. Write: "Today, I..."

You can choose different wording if you like, but I always write the date and time and then "Today, I...." And then I write down the most important things I accomplished that day.

I can't tell you how many times this simple exercise has lifted my spirits after I got to the end of the day feeling like I'd accomplished nothing because I hadn't successfully completed something I planned to do. When I write down what I did get done, I suddenly realize the day wasn't wasted after all.

You can write down as many or as few items as you like, but make sure to include the things that are most important to you. And be careful to only include the positive. I'm often tempted to write something like, "Made progress on an article today, although I didn't complete it as I had hoped to do." Nope. Only include what you did get done.

2. Write: "Priority for tomorrow:"

Again, you can choose different wording if you like. But the important thing is that you choose one priority for the upcoming day. Even though there may be several important things you have to do tomorrow, you must pick the single thing that matters to you most. 

It can be challenging to do, but it's an important exercise because it forces you to think through what really matters most. What's the one thing that, if you get it right, you will feel that you've won the day?

If you're anything like me, this is a very powerful step. I almost always find that, whether I consciously think about it or not, one priority I write down gets my full attention and best effort. It almost always gets done.

3. Make this the last thing you do before bed.

Why? Because research suggests that the last thing you pay attention to before sleep will stay in your mind. This is the reason I try to avoid reading the news at bedtime. It's also why I keep my journal by my bedside, so I can make this routine the very last thing I do before turning out the light.

Giving yourself a jolt of positivity is useful any time of day, but it's a particularly powerful thing to do right before you go to sleep because that too will stick with you. It's sure to better your mood and increase your motivation, and that effect might even last through the following day.

There's a growing audience of Inc.com readers who receive a daily text from me with a self-care or motivational micro-challenge or idea. Many are entrepreneurs or business leaders, and often they text me back about their work, their lives, or their biggest ambitions. (Interested in joining? Here's more information and an invitation to an extended free trial.) My subscribers tell me that when they start the day feeling motivated and positive, it makes them much more effective at work and makes the workday happier too. Spending five minutes to write down today's accomplishments and plan tomorrow's priority can help you get there.