I understand why the concept of resurrection as a reward might be troublesome in light of the fact that people do die young, or in bad physical condition, or maybe don't exactly meet the definition of a saint. Perhaps it bothers you the fact that you may not see that next reality. First, let's understand what it is to the best that we can and perhaps things issues will become less troublesome.
First off is that yes, we do believe in a physical resurrection. It is in fact such an important Jewish belief that one is considered to be a heretic if one doesn't believe it. However, the nature of that resurrection is much less understood. Some sources explain it as it would read literally that we would come back to our bodies as is, like the Ramban seems to say. Others suggest something else is going on, as R' Arye Kaplan explains the position of the Rambam and I have heard reported in the name of the Ari z"l.
The second issue is that the entire concepts of eternal reward and the hereafter are concealed in the Torah for a reason. The Maharal explains in his introduction to his book on the Exodus Gevurat Hashem (The Might of G-d) that the reason these issues are obscured is because they don't make a whole lot of sense in this world and they're concepts we can't easily relate to. After all, as you point out, what kind of reward would it be for a 95 year old man to return to the same worn out body? The Maharal's explanation that this reward his past our comprehension given our relatively limited ability to experience reality makes sense.
The third issue really complicates issues, and that is that we believe in the concept of gilgulim (reincarnation). If people have experienced multiple lifetimes in order to get right what they didn't previously, the question then becomes who comes back. To that I have heard that every incarnation of a person that merits does come back, because they are not actually the same person. That's about the easiest part of the equation.
The most confusing part of it all is when and how this all transpires. There is an interplay of three events in Jewish belief the order of which is quite confusing. We believe in this concept of a resurrection of the dead for those who merit, an Olam Haba (world to come) where people go after they die to receive their reward and punishment (the vast majority of people experience both), and yomot haMashiah (the days of the Messiah). About these issues there is considerable debate and literature. I saw a very good treatment of it in the book Minhat Yehuda, but it's way too much to get into here, as much as I'd like to.