In order to deal with loss of any kind we need something else to depend upon. If we strengthen our sense of refuge in our practice, in the Dhamma, then we have something else to fall back on. We don't have to lose that as we get older. If we strengthen our good Kamma, we do not have to lose that, either. We have to see what we really own and what we do not own. This comes from reflecting on the impersonal nature of existence, and especially from reflecting that material things are not really mine. They belong to nature and they return to nature. This understanding comes upon reflecting on the Four Great Elements, so that we don't take things that are within the realm of material elements and the Four Great Elements to be "mine." If we have this understanding, there will be less of a sense of loss, because, although we may still lose these things, we had less of an idea that they were "mine" in the beginning.
If we place our security totally on external things, then, when we start to lose these, we have nothing to fall back onto. Not having that sense of security and losing control of our life as we age create a lot of suffering for a lot of people. A person may be very dynamic in their prime, but suddenly they can't even control their body any more. They need help to do things we normally take for granted and that we do ourselves. If we do not take the aging of our body personally, then we will be more likely to be able to accept this help gracefully and not take it personally. So it's helpful to strengthen our refuge or our sense of inner security; strengthen our Wisdom of the characteristics of existence, that nothing is really mine; and reflect on death also helps, because we may not actually have the capacity to get old before we lose everything. If we a actually have time to get ready, then we are very fortunate.