Balancing the Scale

When I was young, I had a toy
That was an adding scale.
You hung the plastic numbers
'Til equality you'd nail.

Of course, it only worked
If what you added was correct.
Two twos would balance out a four;
A five it would deflect.

With age I've learned that life's like that,
A scale we mustn't tip,
Though keeping equilibrium 
Means trying not to slip.

To stay in balance is, to me,
Much harder than it seems.
That "gentle stream" that life is called
Is just the stuff of dreams.

My scale of life, most often,
Dangles slightly on a tilt.
A plastic number's not enough
To fix things to the hilt.