Stimulate the death reflection. That's going to be the number one way to develop more energy in the practice. But let's be clear, there's energy on two levels: the mental level and the physical level. As you increase in years, the physical level just isn't quite the same. But the mental level doesn't necessarily have to decrease. For many of you, there's plenty of scope to increase it. So by reflecting on death, keeping that in mind, it stops you spending so much wasted energy in frivolous activities and encourages you to put more energy into your spiritual growth, your mental development. That in itself is possibly the number one way for bringing up energy for the Dhamma practice.