The mayor causes of death are health related, most of them are related to lifestyle. So the most effective way to life longer in general is a healthy lifestyle. Staying in shape and eat healthy not only extend your expected life expectancy, but also improve quality of life. So getting/staying in shape should be something you should have as goal.

Being fit in a survival situation is obviously very handy, but should be a secondary reason to be fit. You (hopefully) don’t end up in those situations regularly.

Training wise, well my job relates to training emergency personal. So I know how important it is to be trained. Skills fade if you don’t use them. Skill requirements changes. People change. Equipment change. Always make sure you not only think you know how to do things, but also actually done it. Some things cannot be teached from a book. Some can, but are not described in such detail in books/instructions. It’s sometimes really the small things that matter.