Ground spice loses most of its aroma within a few months of opening, long before the date on the packet suggests anything is wrong. The date measures safety, not flavour.
Start with where the jars live. A rack beside the stove is the most common place to keep spices and the worst one: heat and steam both drive off the volatile oils that carry the smell.
Use glass with a tight lid rather than the bag the spice arrived in. Every time an open packet is folded shut it traps a little more air, and air is what turns turmeric dull and cumin flat.
Where you can, buy whole and grind small amounts. Whole cumin, coriander and cardamom hold their aroma for a year or more; the same spices ground keep it for a season.
Finally, only ever use a dry spoon. Moisture from a wet one is what spoils most jars, and it happens long before anyone notices.