That could be reviews with employees, marketing tasks, personal things like running, going to gym, etc.

TI...aka Tenant Improvements...your future tenant may want to negotiate different terms for the move in, like a few months discounted rent(this could be on top of the above mentioned vacancy) while they build out the place, or some concession for the Tenant Improvements, if you  have an empty shell it could require extensive work to make it business ready for different types of business, think needing to add bathrooms for a gym(dozens of showers and toilets, lockers, etc) or adding a fully equipped commercial kitchen(walk in freezers, special fire suppression, a few extra sinks or drains) With apartments, I rarely have to do extensive build outs or concessions for tenants, even if I have full on renovation, it is almost always replace the old with same but new, ie tear out old kitchen put new kitchen in same place, same plumbing, just new cabinets, and flooring(if you are at all handy, you can do most of it yourself, or be able to estimate accuracy of bids easily).

I will take a look at that now while I’m hitting the gym! 

The next rental covered my personal HOA fee, the one after that my car insurance, gym membership, and a couple other bills.

For us it's been fitness (gym/bicycling), hobbies, and travel because we're pitching pennies on rehabs. 

I try to go to the gym 5 to 6 days a week, and go for an intense power workout at least once per week.

Your gym, church, work people need to know what you do.  

I go to the gym, get groceries, run errands during the day.  

And you destroy your credibility.A huge super secret of mine to stand out and be credible... believe it or not.. is go to the gym.

You two @Alexander Felice and @Spencer Cornelia would be billionaires by now if you spent less time in the gym and more time talking to ME!