The question you have to ask is, who are you hearing this from? The answer is: people with a vested interest in making you believe the economy is doing great, or people fooled into believing this by those with a vested interest.
I suggest you closely examine the metrics used by those who claim the "economy is great". First these metrics are usually comparing year-over-year changes to point to "positive changes" in the economy. What they fail to announce is that the formulas they use to calculate these metrics are "adjusted" regularly to ensure that the numbers they seek are reflected. CPI is a perfect example. The FED claims that inflation has been very low, if not non-existent for years (good for workers, since their wages have fallen or remained stagnant for decades). Some have noted, however, that prices for most of the things people need to survive (food, rent, education, healthcare, insurance) continue to rise dramatically. How can this be? Well one way the FED lies with their numbers is through a mechanism called the "hedonic adjustment". If you paid $2 for a roll 60-sheet roll of toilet paper last year. This year you paid $3 for a 60-sheet roll this year, that's some serious inflation, right? Not according to the FED. The FED claims that the quality of the toilet paper is better now. Even though you are paying 50% more, the FED says the toilet paper is 50% better, so there is no inflation. How are these "hedonic adjustments" calculated? Arbitrarily by FED functionaries, in a black-box.
Rising debt, falling and stagnant wages, higher prices, consolidation of wealth - these are the real conditions we face and why our economy is lagging. Many will look at you as if you are wearing a tinfoil hat if you question the "official numbers", but even casual scrutiny of the methods and metrics used (the ones they do release) will raise substantial doubts about their worth.