Step 1: Slowly, over the course of a month, let yourself get dehydrated. It is important that you do it slowly so that you do not realise what's happening and attribute your feeling shitty to a cold you cannot shake because you've been on the go non stop for ages.
Step 2: Wander around for weeks feeling like shite and unable to do anything worth a damn beyond watching videos in bed all evening.
Step 3: Think back over the past while and realise how little water you've drunk and how hot it's been lately.
Step 4: Call yourself names, drink loads of water.
Step 5: Feel absolutely fantastic relative to how you felt before.