This afternoon I was waiting at the crosswalk to cross the street by my house. A car coming from the left saw me, and pulled to an abrupt stop to let me cross.
There was no traffic coming from the opposite direction, so I should have been able to cross. But I noticed that another car, also coming from the left, was traveling rather quickly in a 25 mph zone, and didn't seem to have noticed that the first car had stopped.
Did I cross? No. I waited for the second car to come to a screeching halt, because I knew that if he hit the first car, the first car might jolt forward...and that would have been rather inconvenient for the person walking across the crosswalk...namely, me!
That was only sensible. I looked at the circumstances around me, considered the effects that others would have on me, and the potential consequences of my own actions, and then based on these considerations, chose a course of action. It was only sensible.
I find it interesting that in such a short book as Titus (only three chapters) Paul gives the instruction to be sensible five times! Depending on your translation, the word may appear as either "self-controlled" or "soberly" - the idea is to live your life with serious consideration, weighing consequences before acting. In other words...be sensible!
Here's what Paul says in some of those verses:
It seems like such a simple thing, but how important it is for the believer. We carefully consider the circumstances around us. We consider the ways that others will impact us, and the ways that we may impact them. And then, using good sense and restraint, we choose a course of action which will have the best possible outcome not just for us but for others as well.
Unfortunately, we often we dive headfirst into a course of action without stopping to think whether the thing we are planning to do or say is reasonable, productive, and sensible.
Other translations use words like self-controlled, discreet, and sober-minded, but the idea is the same: live in a way that is carefully considered and reasonable.