The tongue could be a powerful building or destructive tool based on how it is used.
A lazy tongue operates two extremes;
When it keeps silent at when and where it is expected to speak due intimidation, shyness fear or favour.
Again, the tongue becomes lazy when it speaks anything, anywhere and anyhow without breaks.
Do not over suppress or over express with the tongue. Learn to prudently control your tongue for your credibility and the growth of the world at large.