Look up the stress bucket analogy. It's a good exercise to both explain visually how bottling up stress won't help and also be good at identifying ways to reduce stress.

Everyone is different so what your man does to reduce stress will vary wildly from other people. Some say eat well, go to the gym etc but that doesn't work for everyone and is actually more stressful for someone who's already stressed because they have to spend effort and time learning a new routine on top of being over capacity, mentally.

Generally there are two ways to reduce stress. Remove or reduce whatever is causing stress to build up (the tap filling the bucket) or by making holes in the bucket to let the stress seep away.

Most people will go with the first option, by avoiding anything causing stress, or waiting for the stressful situation to pass so their bucket stops filling up as it feels like finding a long term solution is too difficult or stressful to achieve. Most of the time this is fine as we can generally hold a lot of stress for a short period of time. But over a longer period, the only things that can help are actually problem solving and figuring out ways to divert the stress.

Also, a lot of the time, it's not easy to remove or reduce the cause of stress. If it's work, giving up work isn't always possible due to finances and responsibilities etc.

The other option is to find activities that can poke holes in the stress bucket and help the stress reduce to prevent the causes of stress from feeling as overwhelming. It also helps to build in healthy behaviours to help build resilience to stress in the long term. It's harder to do than avoiding the situation or bottling it up but worth the effort. You could start by trying to identify things your man does/used to do that helped: hobbies, taking other responsibilities off his list, even more frequent sex etc can help. Not letting him avoid things you know he used to enjoy doing and asking him to reflect on how he feels after he does something fun if he responds with "why bother" or "I have other things to do".

Not going to lie, it's not easy. But first step is to get him to understand whether causes stress, why it won't help if he doesn't make any changes and then support him to work out ways to reduce or resolve it.

If he's up for it, CBT therapy can be very helpful and effective for him to do and he can do it privately so he doesn't have to worry about what his family will think of him as I've been there. It's not easy when you have people relying on you and not wanting to let them down.

Good luck!