If You Could Rejuvenate Three Parts Of Your Body

Suppose you find a lamp that contains a genie. Suppose the genie grants you 3 wishes to make parts of your body young again. You have to use the wishes by age 55 (before most old age diseases become apparent) or immediately if you are already over 50.

The wishes are for only parts of the body. Each could make an organ (and the skin is an organ) or subsystem (e.g. immune cells or spine) young again. You couldn't wish your entire chest or entire leg be young again. But you could wish your heart or your muscles to return to youthfulness.

Also, you could wish any other single organ (or pairs in the case of eyes, kidneys, or other organs that come in pairs or all the parathyroids that come in quadruplets) to be young again.

Okay, with these restrictions in mind what would you wish to make young again in your body?

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Immediately, I said:  My spine - my back is fucked.  Has been for quite some time, and always will be.
My hearing - It's slowly been deteriorating in the past 5 years.
My heart - Heart disease is in my family.

However, upon further reading, some alternate choices presented themselves which made more sense:

Vascular System - This would greatly reduce the risk of heart attack or stroke among other cardiovascular diseases. But it would also help the brain substantially by cutting back on brain microbleeds, probably reducing inflammation that leads to Alzheimer's disease, and reducing risk of dementia.

Immune System - One of the most interesting research reports of the last year reported aging immune systems become less able to kill early stage cancer cells. If I could know exactly which organ I might get cancer I would opt to rejuvenate that organ. But since I can't know which organ poses the biggest threat the next best way to cut my cancer risk (short of total body rejuvenation) is to make my immune system young again and far more able to kill aberrant cells before they develop into a full cancer.

The Brain - First off, doing to will boost my productivity. Second, I'll avoid the risk of assorted causes of dementia, especially when combined with vascular rejuvenation. Plus, the brain does a lot of chemical endocrine signaling to the rest of the body (e.g. from the hypothalamus). That signaling will be done better by a younger brain.

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So, on further review, I would easily opt for the first (2) alternate choices, but my third choice would still remain my spine.  Living in pain the rest of my life would cancel out the benefits of the other 3 alternate choices IMO.

So, what would you choose?