An old Zen proverb...
Guacamole is awesome and avocados are good for you; therefore eat more guacamole.
In a large bowl, place the scooped avocado and lime juice, toss to coat. Drain, reserving the lime juice, after the avocado has been coated. Add the salt, chipotle rub, cumin and cayenne and mash with potato masher or a fork. Fold in the onions, tomatoes, cilantro and garlic. Add 1 tablespoon of the reserved lime juice. Eat immediately.
If you plan to save for later, squeeze a little more lime over the top and cover the bowl to keep it from browning.