Decks are especially prone to wear and deterioration. Most decks are exposed to the elements 24/7/365. Rain and snow make wood swell. Heat and low humidity make wood shrink. The swelling and shrinking takes a toll on decks, particularly the joists, headers, and pillars supporting the deck. If necessary, crawl under your deck and inspect the structure. Look for signs of rotting wood and insects. We all know how termites love wood.
If your deck is elevated, pay special attention to the supporting pillars, joists, and beams. Some decks are merely nailed to the side of a building. At least once a year the news has a story about decks collapsing and injuring or killing multiple people. The more weight on a deck, the more likely it will collapse. The older a wooden deck is, the greater the chance is that one or more supporting members needs to be replaced.