Retain something of yourself, always.
Many non believers such as myself find sanctuary in church buildings. There is much that is hidden from the average eye if one looks around. The first picture is of an Ordinance Survey mark in London. The second is a largely disused church in Birmingham. Such a waste.
Where is your Safe Haven? It is where you feel most at home.
Your safe haven may be your home, it may be your friends or a place that you love to visit. It may be all of these things. It is the place that nourishes and refreshes you.
Your safe haven is also your identity. When you feel it is safe to be yourself you will experience a sense of rest and peace.
The size of your safe haven is determined by the number of people with which you can assert yourself. You must fight for your safe haven if you are in a relationship because an insecure partner may see this as distance between the two of you. Ideally both of you should have your own safe havens that you retreat to when tired or stressed. This means you will not take problems out on one another.
Any person who surrenders his hobbies, his friends and his opinions will become a shadow of their former self and his partner will hold him in contempt.
A single person also has threats to their safe haven but they are easier to deal with. Your employer will try to colonise your time. The state will forbid your unacceptable opinions and mainstream culture will make your hobbies seem foolish and childish. The only way to resist this is to have sufficient money to leave ones job or even ones country if this becomes necessary.