... it seems like more and more people having these nowadays. Or they've just learned to finally notice it. I know that young people have such issues too, to the older generation's surprise (to quote my mother, "How can you even suppose that you are depressed?! You're too young! You're imagining things").
Not to be hard on your mother, but depression isn't solely the result of external circumstances -- such as the cumulative burden of losses/disappointments over the course of a lifetime, if that's what she's thinking.
A lot of what's changed over the past 30-40 years is recognizing that at least a part of depression is chemical (although that varies from person to person, of course). It has to do with a deficiency in brain transmitters, the same way that diabetes or anemia stem from other chemical deficiencies -- and like those disorders, it can be addressed medically. None of them mean anything's "wrong" with you. It's just that we're complex creatures, and sometimes our ingredients get out of balance.
The wild card is that depression affects mood and thinking, so it can actually "beat a path" more heavily in negative parts of your mind that can make you even more depressed because you isolate yourself, have less energy to do stimulating things, etc. (And that's one reason to get clinical depression checked out sooner rather than later: so your brain doesn't wear a groove into the dark parts.)
Of course, taking a pill by itself isn't the solution. Just like with diabetes or anemia, lifestyle changes help. For example, I am a couch potato by nature, but I recognize that exercise really does help lift the mood. It has to be the right kind of exercise for me, though -- namely, a group exercise class (e.g. I
have to show up at a given time/place, and I have peer pressure not to quit midway through) that's not too hard, and has music I like. For other people, it might be an hour of weight-lifting, blissfully alone.
Plus, there could be cognitive or behavioral therapy (it doesn't have to be the old Freudian model seen in so many jokes); prayer/meditation; getting draining influences/people out of your life where possible and bringing in things/people that recharge you, even a good meal -- a lot of different factors that vary from person to person.
But the first step is just to notice what's going on with yourself. The second step is to consider that things
could be different. If you can picture that, a lot of other things become possible.