You would not say "healthful" behavior - say healthy behavior instead. Healthy behavior makes you live longer. Eating healthy foods and getting enough exercise is healthy behavior.
Eating fruit is very healthful
You are not veridical in your assumptions of my behavior
Solitary animals usually exhibit territorial behavior.
His behavior was very peculiar after he received this call.
James was disgusted at her vulgar behavior...
His behavior is so predictable! That was a predictable response.
His tolerance to her improper behavior had limits, he finally broke up with her.
Your continued distasteful behavior risks your expulsion from our staid consortium.
Example sentence - His daughters vindictive behavior caused more trouble than she was worth.
The boy showed his impolite attitude because of his behavior
The foul weather and odd behavior of the villagers were taken as prodigies.
I want to observe the behavior of humpback whales.