It’s supposed to be the season to be jolly - but not everyone feels like celebrating this time of year.

“It’s normal (for some people) to be sad around the holidays,” said Susan Forward, a therapist and author of “Mothers Who Can’t Love: A Healing Guide for Daughters” (HarperCollins). “Part of it is the nostalgia for our childhood and another part is we’re mandated by guilt to be with people (who) have injured us, traumatized us or made our lives miserable.”

Of course, even those with loving families and happy memories can find the holidays a time of inexplicable sadness. Here are some tips to help ensure a happier holiday season.

Take charge of yourself. “You need to really ask yourself, ‘In the whole world, what is under my control?’” said Kelly Minor, a clinical psychologist based in California’s Silicon Valley. “We can’t control what other people do or think. The only thing we have control over is our own behavior.”

Do what you want to do, not what you feel you have to do. “I have a lot of clients who have cut off toxic family members, but when the holidays come around, they feel so guilt-ridden if they don’t include them,” Forward said. “You have to give yourself permission to say ‘no.’ But this is very hard for a lot of people who have major emotional setbacks or disappointments or trauma in their lives. Address these issues with a counselor or therapist so you can slowly gain back your self-respect and do what makes you happy.”

Take it easy: Don’t overbook yourself. It’s easy to do, but it will add stress at a time you least need it, psychotherapist Mark Sichel writes in “Ten Tips to Beat the Holiday Blues” on PsychologyToday.com.

Take three deep breaths. Sense a meltdown coming? “A deep diaphragmatic breath puts you into what is called the parasympathetic nervous system, which is the calm nervous system,” Minor said. “The sympathetic nervous system is ‘fight or flight’ and that’s when we say the things we wish we hadn’t said or when we’ve run out the door. Take three deep breaths and track the beginning, middle and end of the inhale, and the beginning, middle and end of the exhale.”

Don’t stay long. Bonnie Eaker Weil, a relationship expert and author of “Make Up, Don’t Break Up” (Adams Media), said it’s important to set boundaries on how long you stay at certain gatherings.

“This is what I call ‘doing a short run,’” Weil said. “For those people you’re anxious about seeing, tell them that you’ll be passing through or stopping by for an hour because you have another stop to make. And be sure to tell them before the day of the event so they don’t seem surprised.”

Get support from your partner or a friend. “A 20-second hug can cause a dopamine rush,” Weil said, referring to the neurotransmitter that controls the brain’s pleasure center. “So if you are really struggling … pull your partner aside and ask (him or her) to give you a real, meaningful hug. That connection will immediately give you a boost.”

Plan activities that uplift you. Whether it’s a trip to the spa, an extra yoga class, taking a holiday craft class - any activity that calms you, Sichel writes, gives you a better perspective on what is important in your life.

Safety in numbers. “Those people you don’t like or can’t stand are much more tolerable when you dilute them with other people,” Weil said. “My father had a hard time getting close with family but when I invited friends over for Thanksgiving, he was nonstop chatting, because it dilutes the intimacy when you have new faces around.”

Get out of the house. Weil also suggests, if it’s feasible, getting out of the house for a walk, group activity or movie - any reason to leave the house “so you aren’t just sitting around drinking and watching television.”

Start a new tradition. Patricia Evans, author of “The Verbally Abusive Relationship” (Adams Media), said a great way to mix things up is to start a new tradition, either with friends or family. “Pick a new venue like a hotel or good friend’s house and do something that you’ve never done before,” she said.

Be around positive people. “If you spend your time around negative people, their energy will rub off on you,” Weil said. “Find positive people who make you laugh and avoid the Scrooge. If you feel the Scrooge start to bring you down, walk away. If you are the Scrooge, you need to make some changes so you aren’t the person everyone is trying to avoid!”

Take care of your body. “One way to lift your mood immediately is to get exercise, so work out every day if you can,” said Weil. “And be sure not to drink too much or eat too much sugar.”

Don’t bring up the past. “It’s not where you’ve come from, it’s where you finish that matters,” Weil said. “Take the negative and see it as a positive because those negative incidents made you a stronger person and also gave you better skills to deal with uncooperative people.”

Respond, don’t react. “We need to know the difference between reaction and response,” Minor said. “People react when they think they’re actually responding. We’re putting 100 percent of our energy on what we have zero percent control over - which is what our family members think, feel or do. Responding is saying to yourself, ‘In this moment, what’s under my control, and what choice do I want to make?’”

Love yourself. “Self-love is never selfish or unhealthy, unless it gets grandiose and totally narcissistic,” Forward said. “You have got to recognize that you are as important as anybody else. We’ve all been so brainwashed to put other people first, and if you put other people first, that puts you last. I don’t mean you can’t be loving and kind and nurturing to other people - of course that’s where you want to be. But you also have to do the same thing for yourself. Otherwise you’ll be depleted and you will have nothing to give your spouse and nothing to give your kids.”