If you start pouring concrete before you’ve built a wooden frame to shape it, you’re going to end up with a big blob. Once the concrete starts pouring, it’s pretty much impossible to build the scaffolding; the concrete comes too fast and is too heavy.
Any new project or endeavor works like that, too. Let’s say, for example, that you have a baby. Imagine coming home from the hospital with the baby as the first step – and only then deciding to look into things like a crib, diapers, baby-proofing, etc. You can see what a disaster that would be! The baby is the pouring concrete; in order for it to pour into the shape you want (in this case, a happy home with a thriving and healthy child), you have to build the wooden frame first. You needed to already have a crib, diapers, formula, an accommodating schedule, family support, etc.
Whether it’s having a baby, taking on a new job, or anything at all that uses your resources, remember – by default, it will not only fill every inch of available space in your life, but it will do so with disastrous results. You prevent that by deciding in advance what shape you want that thing to take in your life, and then building a box for it in that shape.
So before you take on any new responsibility, take a little time and write out what shape you want it to be. Where are its clearly-defined borders? What does it look like inside those borders? Then do a little shopping and a little communicating, and build that frame. Because the concrete pours from day one, so anything past that is too late.