Verbs that aren't

A billion years ago, a writing coach told me that if I wanted to succeed at the craft on any level, that I should avoid the following:

IS
ARE
WAS
WERE

The four weakest verbs in the English language.
The first thought was (is) that there are (is) not much way to avoid that.
Well, yes there is (was).

The trick, you see, is (was) to use verbs that sing, that drive the story. The better the verb, the better the description.
In a sense, the way to make better sentences is (was) to use verbs that do something.

There is a tree in the yard.
The tree in the yard stood like a gigantic monument to time.
It is (was) still a tree, but we have some idea of its dimensions, once we realize that the tree stands in the yard, which I suppose is (was) different from it lying on its side.

Powerful verbs help a writer because powerful verbs create a need to produce better descriptions. Verbs move our lives.

Try it sometime. Take your average sentence, even one so benign as "I am talking on the phone" and turn it into something far more dramatic.

The best authors seldom rely on is-are-was-were for description.

There are (were) times when those verbs are (were) helpful.

Try to think of something better.