The nice thing about grounding is that many of these can be done in any environment.5 You might be home alone or out in public, but once you feel that flashback or dissociation coming on, you can use grounding to move your focus back to the present.
Working on grounding takes dedication and it becomes easier over time. If these particular grounding techniques don’t work for you, try something else. For example, some people find that a rubber band on their wrist is useful to snap them back to the moment. The ultimate goal is to live in the now and focus on the present when the past starts coming up