Completing the London Marathon, all 26.2 miles, is an amazing feat. But what powers up many of the 40,000 taking part in the annual event is that they are doing it in honour of a loved one who has passed away.
As we cheer on – from the comfort of our sofa or as part of the crowds that line the course – the public can acknowledge that person’s grief, and even help pay tribute with them.
And this is just one of the ways that running a marathon can be helpful in getting someone through such a painful time.
Setting a goal like completing a marathon can be a huge step because it releases dopamine, our so-called reward drug, says Dr John Wilson, a visiting research fellow at York St John University and an experienced bereavement counsellor.
This can be in short supply when we are working through grief.
"Dopamine is released every time we achieve a target we have set ourselves, such as hitting a time goal in preparation for running a marathon, and successfully completing it," says Dr Wilson.
As we prepare and log the miles to get ready for marathon day, it can also break the cycle of what bereavement counsellors call the ‘rumination’ phase.
"It’s the most damaging feature of grief," says Dr Wilson. "It’s that same negative thought going round and round in your head, and can lead to anxiety and depression."
He points to the typical pattern of how we grieve as outlined by Margaret Stroebe and Henk Schut in The Netherlands, and it shows that people who do best following a loss will take time out from their grief with a hobby or interest, or by socialising with friends.
"Training for a marathon whilst grieving is an ideal way to achieve that balance between time grieving and time doing other things," explains Dr Wilson.
"The achievement of preparing for and completing a marathon can restore meaning and purpose to your life after a loss, particularly if you are running to support a cause related to your loss, such as a cancer or dementia charity."
And when the big day arrives, the experience of running with a group can be incredibly helpful.
"When we exercise in a team, we release oxytocin into our bloodstream. Running the marathon with friends would probably help best with grief, but so will feeling the unity with all the runners."
Watch: Runner to complete London Marathon backwards in support of Ukrainians affected by war
Dr Wilson adds that our cheers can really make a difference – and who hasn’t cheered that little bit louder when reading the poignant tributes on runner’s vests? "The support of the crowd will help."
He also has some encouraging words for runners to take with them on Sunday.
"Imagining your loved one looking down on you and spurring you on helps to create a loving bond which can continue into your future. It all helps in coming to terms with your loss."
Of course, running won’t provide all the answers, but it can help people move forward during a painful time in their lives.
What ‘feel good’ chemicals are released by running outdoors?
The four ‘feel good’ chemicals, produced by strenuous exercise, such as running a marathon, are dopamine, serotonin, oxytocin and endorphin. "You don’t have to take these as pills, because given half a chance, your own body will make them for you. These neurotransmitters are released by your brain into your bloodstream," explains Dr Wilson.
Dopamine: Known as the reward drug. That warm, satisfied feeling you get when you have achieved something, is dopamine in your brain having its effect. Bereaved people release dopamine when they recall happy memories of the loved-one they have lost.
Serotonin: Is the happy drug. It also helps regulate our sleep patterns. Serotonin is made from an amino acid called tryptophan, which you get from a balanced diet. Tryptophan-rich foods include chicken, turkey, red meat, fish, milk and eggs. For vegans, tofu, oatmeal, nuts and beans. The kind of balanced diet that a marathon runner would have in preparation, will also help with grief.
Oxytocin: Is sometimes called the love drug. It is produced in your brain and released into your bloodstream by your pituitary gland, which sits just under your brain and above the roof of your mouth. Oxytocin bonds us to other people.
Endorphins: Our natural opiate, for pain relief. When we are injured, our brain releases endorphins. Since both physical and emotional pain are experienced in the same brain region (the periaqueductal gray, also known as the central gray), perhaps we are flooded with endorphins to get us through the first few days of a bereavement. Maybe that explains the numb, 'don’t feel anything' mood of early grief.
Dr John Wilson is the author of Supporting People through Loss and Grief: An introduction for Counsellors and Other Caring Practitioners and The Plain Guide to Grief.
Watch the London Marathon on BBC1, BBC2, iPlayer and online on Sunday 23 April.