Samaritans wants to turn the third Monday of January, known by some as Blue Monday, into the more positive Brew Monday, encouraging people to make a cup of tea and have a chat on the phone or online with those they care about.
The Great British Bake Off finalist and Samaritans volunteer Laura Adlington said it is about "making sure that people are all right, not just on that day but every day".
Blue Monday is seen as a time when people's mood may have dipped as the festive season is over, bills may have arrived, payday is still some way off, the weather is gloomy and new year resolutions may have been shelved.
This year's Blue Monday falls during a lockdown in a worldwide pandemic, meaning that challenges faced by many people in winter will be felt even more acutely.
Adlington said she has had days where she has not wanted to get out of bed and rather than talking to people has felt like she has wanted to "shut the world out a little bit".
But she added: "What I've made myself do recently is reach out to people and talk, and it does help, it genuinely does help."
Adlington said the ethos of "a problem shared is a problem halved" may sound archaic but there is a lot of truth in it.
"Bad days can seem eternal, but they really aren't. What you're feeling now is temporary," she said.
Talking about Brew Monday, Adlington said: "Let's reach out, let's talk to people, and let's have some meaningful connection and get talking, rather than kind of sitting and feeling sad and feeling alone in our sadness. We're not alone."
She pointed out that Samaritans is not just for people who are feeling suicidal, but also for people who are in crisis or "just having a really tough time".
She said the service is available 24 hours a day, seven days a week, adding: "There is support available. Don't be afraid or ashamed to seek it out."
Adlington, who has been a Samaritans volunteer for two years, said: "If 2020 has taught us anything it's to be kind.
"If you think someone is struggling, ask them if they're OK. You're not going to make them feel worse.
"You don't need to have all the answers. A phone call is such a small thing, but it can mean the world to someone."
Samaritans chief executive Julie Bentley said: "The challenges many people face during winter have been felt even more acutely this year with the pandemic restrictions.
"At Samaritans, we know how powerful talking and listening can be, even if it is virtually.
"It doesn't have to be a Monday or a cup of tea, it's about taking the time to listen and support one another. It could save a life."
Samaritans said it found that 58% of UK adults felt that speaking regularly to friends and family either on the phone, via video calls or in person over the last year had a positive effect on their mental wellbeing.
The charity's research also found that simply knowing someone who cares for your wellbeing is there for you, can make a big difference.
The research was carried out by YouGov from November 27 to November 30 and included 2,075 UK adults.
Anyone can contact Samaritans free any time from any phone on 116 123, even a mobile without credit.