Energy for the practice. It all hinges on how much compassion you have for yourself. It is as simple as that. Now I am not sure if any of you have a complete set of false teeth. Some of you may have a few holes, etc, but generally I would think all of you brush your teeth every day. You have energy to brush your teeth every day. Maybe occasionally you are flying across the country or whatever, you miss it, but generally you brush your teeth every day. You have the energy to brush your teeth every day. Why? Because you know the Dukkha of not brushing your teeth every day. You are going to get fillings, you are going to lose your teeth, it is going to hurt, you are going to waste money at the dentist and so on. So you understand the Dukkha of not brushing your teeth, you have compassion for yourself you don't want that Dukkha, and therefore you brush your teeth. It is automatic. Because you have compassion you will make the effort.
As far as energy in the practice goes, you need to have compassion for yourself on all of your mental levels. You don't want to be angry any more - you need to work on Compassion/Lovingkindness. You don't want to get lost in all of your future thoughts - you need to work on death reflection. So on each of these different levels mentally, if you open the compassion for your own mental problems then the energy is going to come to do the work in the practice to end your mental problems.