Take off is optional
Landing is not. Airplane pilots use this phrase to remind themselves of the harsh reality that leaving the ground is not required — but returning to it is. I imagine the phrase was introduced to help pilots remember to check all of the appropriate items off of their list before they go wheels up.
If a pilot finds a problem with her aircraft or her flight plan while she is still on the ground fixing it is not a major problem. If she discovers the same problem while she is in the air there is a good chance she will find herself in an emergency situation.
For some reason we often fail to apply this basic rule in our daily lives. We quit our jobs to pursue passion projects without the required experience or financial backing and act surprised when things don’t work out. We purchase expensive things we can’t afford on credit and get upset when the bills keep piling up every month. We jump into relationships before getting to know the other person and become frustrated when they don’t turn out to be exactly who we had hoped.
Gravity is much more forgiving when you’re already on the ground.