You can Listen here! First let me define what a “Side Project” is. In this case a “Side Project” is something you are not being paid for and something that you have complete control over. It can even be something you are just trying out some new ideas on. The reason it can not be something you are being paid for and ideally something you are fully in charge of is so you’re not under any pressure to deliver but you have time to explore, to learn, to try new ideas and overall build confidence.
A sprint starts and you feel unsure or overly sure of being able to complete all the work in that sprint. And depending on that you crank at the start working long hours in stress of not getting done in time or not enough focus (too much twitter) thinking you have it under control only to stress at the end of the sprint! It would be as if I started out for a jog not knowing how long the route was in a full sprint.