Anton Chekhov gave this advice to a writer: “Don’t tell me the moon is shining, show me the glint of light on broken glass.”
The way to make a character or a setting or an action come alive in the imagination of the reader is to provide specific details. Compare these two descriptions:
Howard was a clinically obese man. He found it difficult to walk very far and stopped frequently to rest.
Howard wheezed with the effort of carrying his weight. Every ten steps he had had to stop and lean against the nearest wall.
Not only is the second description more specific (not just stopping but leaning against the nearest wall), it brings in another sense--the sound of wheezing. The more you can bring in not only what things look like but also their smell, their feel, their taste, the more real they become to the reader.
Often the best specific to mention is one that is unexpected. For instance, it might be that despite his bulk Howard has dainty feet.
Different details will have different effects in terms of how the reader perceives the character or the setting. For example, if we want the reader to feel some sympathy for Howard, we might show him enduring the embarrassment of having to buy shoes in the children’s department.
One warning: don’t overdo it. It’s easy to overload the reader with details. Adjectives are especially dangerous! One usually is enough. “Grimy fingernails” is fine; “Grimy, misshapen, yellowed, gnawed fingernails” is too much.
Adverbs can be even worse--generally it’s better to describe the action rather than characterize it. For instance, instead of “He ate the donut greedily,” you might write, “He stuffed the entire donut into his mouth so fast that jam squirted out of his mouth.”
Checking to make sure that you have been specific in your descriptions is one of the key things to do when you go over your first draft.
If you want to see how it's done, read some of Chekhov's short stories. They constitute a great masterclass.
(And to learn even more, see my book, "Your Creative Writing Masterclass," published by Nicholas Brealey. Not only does it contain more of Chekhov's advice, but also guidance from Dickens, Austen, Hemingway and many others. You can get it from Amazon or your other favorite bookseller.)