THE PROBLEM: By 3 p.m., you're nodding off at your desk.
THE FIX: Simply standing up gets more blood — and energizing oxygen — pumping to your brain; after walking briskly for a few minutes, your whole body (including your sluggish mind) becomes more engaged. "You don't even have to work up a sweat," says Robert E. Thayer, professor of psychology at California State University Long Beach and author of Calm Energy: How People Regulate Mood with Food and Exercise. In one of Thayer's studies, subjects either went for a brisk 10-minute walk or ate a candy bar. The walkers had increased energy for up to two hours, while the snackers saw their immediate energy boost drop off within an hour — and after two hours were even more lethargic than before.
TRY THIS: When you have time for more than a couple of laps through your cubicle maze, personal trainer Kacy Duke of Equinox Fitness recommends circuit work for the biggest jump-start. Count to 10 jumping rope, then do 8 push-ups, then 12 crunches. Next, graduate to 20 seconds jumping rope, 10 push-ups, 15 crunches. Keep upping the ante until you've been active for at least 15 minutes. (Don't push yourself for more than 30, though — the idea is to get energized, not exhausted.)
BONUS: Whatever workout you choose, do it outside when possible. Research has shown that an identical workout will yield a more substantial energy payoff when it's done outdoors — "even when the sun isn't shining," says Thomas Plante, professor of psychology at Santa Clara University, who has published several dozen studies on exercise and mood.
THE PROBLEM: It's been a couple of weeks, and you can't seem to snap out of this woe-is-me funk.
THE FIX: Even short bursts of exercise (again, we're talking 10 minutes) can elevate the serotonin and norepinephrine levels in the brain that perk up your mood, while longer-term workout regimens have proved comparable to prescription antidepressants. One particularly rigorous study, published in the Archives of Internal Medicine, found that people suffering from clinical depression who exercised — walking, jogging, or biking for 30 minutes three times a week — for four months reported increases in happiness and self-esteem in line with those who had been taking Zoloft for the same period. And working out with music or a friend has also been shown to augment the antidepressant effects of exercise. You might want to avoid the gym, though — it's a hotbed of what psychologists call "social comparison." "You can start thinking, These people are more attractive, more fit than I am, and walk out of there more depressed," says Plante.
TRY THIS: Movements that are literally uplifting are most likely to boost your heart rate and your spirits, says Duke, who likes to take clients through a series of jump squats when they're feeling blue. Start in a deep squat position with your arms stretched out in front of your body, then jump as high as you can, reaching up toward the ceiling. "After doing them, it's hard to feel powerless anymore," says Duke. "And using only your own body weight — no machines — improves your sense of self."
THE PROBLEM: Your passive-aggressive boss has been in rare form today, and by 6 p.m., every pore of your body is ready to scream.
THE FIX: Pass on the kickboxing class. A regimen that emphasizes deep breathing and lets you get into a smooth flow will stimulate the parasympathetic nervous system, which is responsible for calming the body. "When exercise is rhythmic and predictable, as it is in yoga or even free-weight training, you don't have to pay much attention to the movements and can focus on diaphragmatic breathing — from the belly, not the chest," says Kate Hays, a sports psychologist and author of Move Your Body, Tone Your Mood. "After about 20 minutes, tension starts to decrease."
TRY THIS: You guessed it — yoga. Just one session has been shown to decrease cortisol, a hormone linked to stress, and increase the neurotransmitter GABA, which is associated with feelings of calm. Focus on poses that lift the chest for the most intense stress relief. "When you're feeling anxious or frustrated, your shoulders tend to roll forward," says Patricia Walden, a yoga instructor in Cambridge, MA, and coauthor of The Woman's Book of Yoga and Health. "Movements that open that area — even just taking your arms over your head and looking up to the sky for several seconds — can help." Other poses to try: back bends and the cobra (lying on your stomach, keep your legs on the ground and push up with your hands to expand your chest).
THE PROBLEM: You're trying to get eight hours, but you can't seem to stay asleep.
THE FIX: "Any type of aerobic exercise is good for improving the length and depth of your sleep," says James B. Maas, Ph.D., professor of psychology at Cornell University and author of Power Sleep, who recommends shooting for 30 minutes of heart-pumping activity between 5 and 7 in the evening. If your job, social life, or both makes this impossible most days, just be sure to avoid exercise within three hours of bedtime. "You need to give your body temperature and all the systems stimulated by exercise time to cool down," says Neil B. Kavey, Ph.D., director of the Sleep Disorders Center at Columbia-Presbyterian Medical Center.
TRY THIS: The best exercise to do before lights-out involves no movement at all. Lie on the floor, bend your knees, and rest your calves on the couch. Drop your chin toward your chest, place your arms a few inches from your sides, and close your eyes. Duke likes to lead herself through a meditation session before bed, slowly thanking each part of her body for everything it's done that day. It may sound hokey, but she's on to something: Many studies have shown that expressing gratitude reduces stress.
THE PROBLEM: Your mind feels slow and foggy and...what were you saying again?
THE FIX: Quick — when's your best friend's birthday? What's the name of the main character in the novel you finished last week? If you can't remember, exercise might help. In a groundbreaking study published by the National Academy of Sciences last year, subjects who did cardio exercise for one hour (including 40 minutes on a treadmill, StairMaster, elliptical trainer, or stationary bike), four times a week for three months actually grew new cells in their brains. The workouts not only induced new neurons to form in the hippocampus, an area of the brain pivotal to memory, but also increased levels of BDNF (brain-derived neurotrophic factor), a protein that strengthens connections between those neurons, says Ana Carolina Pereira, the Columbia University neuroscientist who led the study.
TRY THIS: Pretty much any aerobic activity will help create a stronger, faster mind — but why not grow neurons and start putting all that extra brainpower to good use? Sign up for salsa dancing or the jujitsu class you've been wondering about so you can learn something new (and actually remember it).