[oshirisuki]

work out, you don't necessarily need to spend money on it (I may be assuming money's a concern for you, maybe it isn't?) if you are suffering from depression, you could also consider therapy, if that's a viable option

interacting with people in some way, specially family (if you have any left), is likely to improve your mood

you don't mention where you live, but given that you know English, if it's not something undesirable, consider teaching it, while having some sort of qualification/certification might be useful, what's important is that you know it to teach it, at least in a "getting people to talk" way

another job option that seems viable (at least to my mind) is becoming a teacher of what you studied

for the "wife and kids" thing, I don't think I could give advice, I myself have been single for over a decade