To Feel Better Tomorrow, Do This Today

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Taylor Swift's new song Opalite is all about transformation. She sings about turning darkness ("onyx nights") into brightness ("make your own sunshine"). Like the shimmering human-made gem it's named for, the song reminds us that happiness isn't found, it's created.

Swift's lyrics show that mindset is within our locus of control. With some reframing and Swiftie affirmations, setbacks become "just a temporary speed bump," "failure gives you freedom," and when life gets challenging, "don't sweat it, baby."

One lyric in particular, the black-and-white "you're starving 'til you're not," reminds me of a new study (Le et al., 2025) in Psychology of Sport and Exercise. The researchers found that the main difference in people's next-day happiness boiled down to how much time they spent sitting. Or, in Opalite-inspired terms: "You're either sitting or you’re not."

5 Mutually Exclusive Daily Behaviors

The study looked at how people divide their time each day among these five mutually exclusive daily behaviors and how time spent doing each predicted next-day mood:

1. Sleeping
2. Awake in bed (scrolling, reading, rumination)
3. Sitting (sedentary behavior)
4. Light activity (casual walking, standing, housework)
5. Moderate-to-vigorous activity (MVPA) (brisk walking, jogging, cycling)

You're always doing one of these five things: in bed, awake or asleep, sitting still or moving, or doing light activity or MVPA.

The study's key insight lies in treating these behaviors as mutually exclusive, zero-sum choices. Time spent in one behavior comes at the expense of another, and today's trade-offs influence tomorrow's mood.

Movement Today Shapes Tomorrow's Mood

For this study, researchers tracked 354 healthy young adults (average age 22.6) for one to two weeks, using wrist-worn monitors to capture every minute of their 24-hour cycle. Each night, participants rated their mood based on how positive, energetic, or calm they felt.

Using advanced modeling, the team compared each person's day-to-day shifts. As mentioned, the most significant finding was that when someone spent less time sitting and more time moving lightly, they felt better the next day.

These changes happened based on each person's daily routine. It wasn't that active people were happier overall; even small personal shifts predicted better next-day mood for that individual.

In an October 2025 news release, co-author Yue Liao from the University of Texas at Arlington Department of Kinesiology said:

"[Our] study indicated that light activity—where you don't have to go to the gym or do intense exercise—can lead to better feelings the next day when it replaces sedentary behavior. One doesn't have to think, 'I have to run,' or 'I have to do these big things.' Just sitting less and moving more can have an immediate impact on your mood the next day."

Don't Sweat It, Baby: Not Sitting Boosts Next-Day Mood

Reallocating just 30 minutes from sitting to light physical activity boosted “high-arousal positive affect," which includes feelings like enthusiasm, alertness, and optimism. Even mild motion today can lift your emotional energy tomorrow.

The reverse is also true: Swapping light or moderate-to-vigorous physical activity for sitting is linked to a dip in mood and slight rise in irritability. According to the latest (2025) research, sleep time, awake-in-bed time, and even MVPA weren't as consistently linked to next-day affect.

The biggest payoff in terms of improving happiness came from breaking up uninterrupted stillness with light and easy movement. As Liao explains, "You don't have to work up a sweat to get benefits. Just moving a little more than your usual helps."

Your Daily Time Pie

The study used a 24-hour compositional model, which treats your day as a fixed pie of behaviors. More time in one slice means less in another. When Le et al. tested "reallocation" scenarios, the pattern held:

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• Swapping 30 minutes of sitting for light activity improved next-day mood.
• Replacing time spent moving with more time sitting had the opposite effect.
• Sleep vs. awake-in-bed time mattered less than moving vs.sitting.

From a time management and habit-formation perspective, you've got 24 hours each day, and every minute counts. Swap time from one activity for another to boost your future mood. Stand up and move around during a work call, walk on your coffee break, or take the stairs for a burst of MVPA instead of the escalator.

Why This Matters

In a world where sitting dominates work, leisure, and even social time, these findings offer an achievable mental health strategy that directly boosts self-efficacy. The authors call their results "stepping-stone evidence" toward defining optimal daily behavior patterns for mood. Whether you spend more time sitting or moving shapes how you'll feel by tomorrow's sunrise.

Take-Home: Make Your Own Sunshine by Sitting Less

If you want to wake up tomorrow feeling more optimistic, energetic, and full of motivation to seize the day, take Swift's affirmation to "make your own sunshine" and combine it with the scientists' advice by reallocating just a bit of your day toward motion. You can't control everything about tomorrow, but you can decide whether to sit through it or stand up.

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