There are times when we get so engrossed in life, that we forget about taking time out to recharge the batteries.
After years of trial and error, I have worked out that when the corners of my eyes start to burn, that is my low-battery notification. Others I have talked with have a similar warning sign - a knot in the stomach, sore or tight shoulders, a heavy chest perhaps, or some other physiological sign.
Prioritise 30 minutes of 'you time' each day to recharge before your low battery sign turns up. Spend just 30 minutes doing what you want to; something that makes you happy, something you get lost in.