One rule of thumb that’s worked well for me over the years is something I call “The rule of three*.” My version of the rule limits my commitments at any one time to three major projects. “Projects” in this case can either be major areas — things like health, family/relationships, a job — or specific major projects or hobbies: moving cities, doing a side business, writing an album, enrolling in a course, serious amateur athletics, etc.

So, for instance: health/rest, family, work. Or in the past it’s been health/rest, work, band/music.

It’s pretty simple math: Each day divides into three eight-hour chunks. For most people it breaks down like this:

• 1 chunk for sleep/rest
• 1 chunk for work
• 1 chunk that’s really more like a half-chunk since often there’s commute/travel time, errands, etc.

What about the weekend? The rule takes this into account (that’s why there’s an asterisk after the three). The full version of the rule allows me to have a fourth project, but it has to be one that can be suspended at any time, indefinitely. The fourth slot is essentially buffer space reserved for when the unanticipated happens: illnesses, family emergencies, surprise commitments (good and bad). While you never know what specific unanticipated thing is going to happen, they happen on such a regular basis (especially if you have kids) that it’s predictable.

But four is the hard limit (and if one of the three projects is especially intense, it almost always takes up that fourth slot.)

If you take on more than four major projects, you inevitably short-change the progress you make in any one area. Worse, if you’re maxed out with zero slack all the time, once the unexpected happens, everything gets thrown into chaos as you try to manage it all. It’s long stretches of these circumstances that increase the risks of serious life impairment — major health issues (e.g. heart attack, nervous breakdown), major relationship issues (e.g. divorce), major reputational crises, etc.

The rule’s usefulness comes when new ideas/opportunities/projects come up. It shifts the question from “Would this be a cool/useful/interesting to do” — the answer is always yes — to “What existing project would I drop for this?”

Because real progress on anything only comes from steady effort over a long period of time (years), it ensures that you will have sufficient resources (cognitive, emotional, time) available to make that investment. More importantly, it buffers you from exigencies that can not only stymie progress, but in a few cases can sideline you permanently.