I exercise quite a lot myself, and whilst I agree it's amazing to maintain good mental health, and can probably treat mild depression, it really isn't going to touch the sides if someone is going through a hardcore depressive episode.
In regards to making you feel numb, I've felt more emotionally numb when not being on them. Yeah, some people have experienced emotional numbness on them, but I'd say them people are in a minority.
I do think AD's are over-prescribed, and yeah, some people will always get adverse effects from them, the same as any drug, but the possible benefits of them FAR outweigh the risk of taking them. Statistics prove this. They've saved literally thousand of life's.
And yeah, the nature of how they work does mean that they take a while to take effect; you need to take them for at least 6 weeks until they're fully in your system. If you've not had any response by then, the doc will then consider upping the dosage, or changing the type of AD to get a better response.
I don't think we should put the OP of wanting to give them a go, that's all.