How do you recognize a weak verb? Look for adverbs!
When you find a sentence in which you give the reader a tag telling how an action was performed, chances are you have a lazy verb–one you didn’t really think about as you plugged it in. For example, if you have a character going slowly to the door, consider whether you really meant sauntered, crept, strolled, or dragged. If your character walked quickly to the door, think about replacing those two words with rushed, ran, dashed, flew–whatever is most appropriate for what you see in your mind’s eye. It’s both more concise and more vivid.