Best advice: Stop smoking. At least stop smoking tobacco and share the weed...

Compared to real smoking, soldering is still hazardous, but relatively safe. I mean, you don't suck in the fumes with a straw at the point they are created (or, do you? - just kidding).

Best thing for soldering: Extract the fumes to somewhere else, preferably the outside.

As this normally not possible (at least in the European winter), use a carbon filter.

Not sure where to get the filters, but you should be able to buy 'activated carbon' (the active agent in carbon filter [well, the name gives it away]) at your local chemist - if at a price. If you want to save some money, use a fan to blow the fumes through some charcoal. Technically the same but probably not as effective.

But even a small fan, sucking the fumes away from your face into the room can thin down the nasty solder fumes. Work in a well ventilated area.

So,
1) use a fan to suck away the fumes
2) get them away - preferably outside or trapped in a filter