Fight Aging!

While differences in mitochondria are clearly very important to aging and longevity, this is not the case for all specific differences between your mitochondria and those of the person next to you. For example, take a look at this paper that draws on the Ashkenazi Jewish centenarian study:

Association of mitochondrial haplogroup J with longevity has been reported in several population subgroups. While studies from northern Italy and Finland, have described a higher frequency of haplogroup J among centenarians in comparison to non-centenarian, several other studies could not replicate these results and suggested various explanations for the discrepancy.

...

There does not exist a universal association of mitochondrial haplogroup J with longevity across all population groups.

It is not at all unreasonable to expect differences in mitochondria between genetic subgroups of the same species to influence longevity - even for the comparatively tiny biochemical changes involved in differentiating one haplogroup from another. Mitochondria are the engines of our cells, and numerous experiments have shown that altering their effective output of damaging free radicals can greatly influence healthy life in mammals. I can envisage future decades in which mitochondrial replacement is not just a matter of preventing the age-related degeneration caused by damaged mitochondria, but also upgrades your birth mitochondria to a more robust version - either discovered somewhere else in the human species or engineered de novo based on what is known at the time.

For all that, these are early days in the underlying science, and haplogroup J doesn't appear to be an important difference.