Hit point systems are great, but combined with aging systems they get into wonky results. Characters tend to get more hit points as they age, which can reflect durability, skill and wisdom, but doesn’t reflect how much punishment a young, healthy body can take. My first attempt to adjust for these factors focuses on hit point recovery. Rather than using a flat 1d3 for all characters, trying use recovery based on age:
19 years and less: 0-2 immediately after combat, 2d2 per day of rest thereafter
20-29: 0-1 immediate, 1d4 per day of rest thereafter
30-39: 1d4 per day of rest*
40-49: 1d3 per week of rest
50-59: 1d2 per week of rest
60-69: 0-2 per week of rest
70+: 0-1 per week of rest
Add Constitution modifiers into your healing rate. Minimum recovery is 0.
Immediate recovery can bring the young back to consciousness from zero or less hit points, but the drop to zero still counts toward exertion.
*Note the increase in the general healing rate. In order to properly incorporate Constitution modifiers, we need a range of 1 to 4.