Despite its popularity, "multi-tasking" does not work.
You cannot give 100% attention to 3 things at once, what you get is 33% attention to each and broken parts.
Don't measure anything while talking on the phone!
When in doubt, make a list and follow it. There is no such thing as too small to matter: when you do these things correctly, your peace of mind is much better.
Military put removable tags in huge red letters like "NO STEP" on the weak part of the plane's wing because otherwise the pilot will put his foot through it, "NO START" on the steering wheel of a race car which doesn't have oil in it yet, etc.