If you remember the four stages of mindfulness, sometimes we're having an experience, yet we don't know what's going on. It's after it's all over, we reflect about it, try to learn how we could do better, how we did not do better. Later when our mindfulness and understanding get deeper, we find that we're in it and we've become aware. We find it at the beginning, we find that we understand the conditions beforehand, and so on. So sometimes there's energy and sometimes it dissipates and to know when to put forth more effort and energy, you've got to reflect on what just happened. When did the energy dissipate, and when it dissipated, why didn't it stay, what actually happened, what were the thoughts in the mind? If you can identify why, then you can try make antidote thoughts, to bring in wise thoughts that will get rid of those thoughts that were obviously unwise and dissipated your energy. Why is it a lot of people lose their energy in any endeavor? Because they have idealism, they want the results too quickly. When the results don't come real quick, they lose interest. Interest is the key behind energy. If there's any single thing behind energy it's this, the key is "Interest."
Imagine you've been working 3 weeks flat out in a job, you're exhausted. It's been overtime every day, working Saturdays as well. The project is finally finished, Friday afternoon, everybody's happy, and you're totally exhausted, you just want to go home, go straight to bed, maybe grab a little juice, don't even want to eat, you just want to sack out for 12 hours straight. So you're going home, you're totally exhausted, no energy at all, you get to your door, you go to open the door and you see on the door a note, it goes "Hey Steve, I'm in town! Haven't seen you for 3 years, can we get together tonight? I have to leave tomorrow." Are you going to have energy? Yeah, you haven't seen that good friend for 3 years, they're in town just for the night, you're going to spend time with them that night. And all of the sudden the energy comes out of where? Some would say out of nowhere, I would say out of interest. So energy can be sparked with interest.