I've taken anti-depressants for the better part of 5 years. I found that it took about a month to have a measurable result, and then It took probably about 2 years before my doctor and I got the right dose. In contrast to many, I've had pretty good success with them, but in my opinion many people have unrealistic expectations of what they are going to do and what they are for.

1.) For most people, they will not be a permanent fixture of your life. Many people just need a leg up to get out of a particularly bad period in their life, and when that's over, they no longer need the medication. You can't just stop taking them however, because your body has adjusted its brain chemical levels over time to work in sync with them, so you have to slowly wean yourself off, or you're probably going to have a serious drop in mood, which makes you think that you need them still.

2.) If you're numb, you're either on too much, or on the wrong medication. many people, especially those who took medication at a young age, have this experience. The truth is, when a doctor prescribes antidepressants to you, they're throwing something at a wall to see if it sticks. If not, they've got a whole bucket full of other drugs that they can throw at the wall to see if they stick. We don't know nearly as much about brain chemistry as we'd like, so it's a little bit of an educated guessing game.

The other truth is that antidepressants are not always useful for teenagers, and occasionally make them worse. Just because they didn't work when someone was 16 doesn't mean they won't work when someone is 26.

3.) Antidepressants don't make you feel happy. If they do, again, you're on the wrong shit or too much shit. What they do, broadly, is allow you to be in a headspace where you can DEAL WITH YOUR SHIT. Your mood will usually be neither too high nor too low, and they allow you to be able to get your ass out of bed in the morning, instead of not being able to get out of bed until 3:30 and you've already missed two of your classes today so what's the point of going to the other ones and dinner is soon so you should eat something because you haven't eaten all day but you don't want to go outside because you haven't showered in 6 days and maybe if you order from your usual pizza place the delivery guy won't judge you if you pretend to be doing a hardcore cram for an exam the next day...

antidepressants help with that, but they're not a pancea. They need to be combined with a desire to deal with your shit, a desire to have a healthier diet, and a healthier active life.