Prepare gelatin according to package directions, and let cool on counter or in refrigerator until syrupy but NOT solid. (If it cools too much, you can re-melt it by microwaving it for a little bit.)
In a separate bowl with an electric mixer on medium speed, beat the cream cheese until smooth. Slowly pour in the cooled gelatin a little bit at a time, letting it fully mix into the cream cheese until completely blended together.
Meanwhile, layer pineapple, celery and carrots evenly in bottom of 9x13 inch glass dish. Pour gelatin and cream cheese mixture over all and cover with plastic wrap. Refrigerate until firm.
To serve, cut into squares and place on lettuce leaf. A small dollop of sour cream, mayonnaise, or whipped cream is a nice addition. Makes 12 servings. Enjoy!
Note: If you like the salad chunkier, use cold cream cheese instead of softened. It will break up into little bits that will spread throughout the gelatin instead of smoothly blending in.