The worst part of injury often isn't the pain but the ongoing psychological withdrawal from exercise.
Luckily, there is a way to minimise the strength losses caused by a single limb injury.
A large percentage of the strength in a limb isn't caused by muscle size (cross-sectional area), but by neural factors - that is, the nerve telling the muscle fibres what to do in efficient and coordinated ways.
The valuable thing is, you can continue to train the neural patterns of an injured limb even if you're not using it. This is called 'cross-education'. Cross-education refers to the fact that if you have an injured arm or leg, by training THE OTHER arm/leg, you are maintaining the neural patterning in the injured arm. So even though you may lose some muscle, your movement patterns are maintained, and strength losses are minimised. So drag out those kettle-bells and dumbbells and start working the good limb.
You can also use injuries as an opportunity to work on your weaknesses.