Ca va? is how are YOU doing.
Now, how do I ask specifically - how is your job(hobby/health/whatever)?
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Actually you can keep the "Ça va ?" phrase and apply it to the job, health, or whatever you want to know about.
1) Comment ça va, au travail ?
2) Comment va ton travail ?
3) Comment ça va, ton travail ?
4) Ça va, au travail ?
5) Ça va, ton travail ?
6) Et le travail, ça va ?
1) How is it going at work?
2) How is your job going?
3) How is it going, your work?
4) Is it okay, at work?
5) Is it okay, your job?
6) And about your job, how is it going?
Number 3) is the least correct among all those but when speaking orally it most of the time is okay. For example if you were talking about health it would sound totally normal to say Comment va ta santé ?, especially if the person recently have had health problems. For some reason it does not sound that good with work/job but I hardly can figure out why.
The best you can do is to use number 1), it should work in almost any case :
Comment ça va, au travail ?
Comment ça va, ta santé ?
Comment ça va, avec ta femme ?
How is it going at work?
How is your health going?
How is it going with your wife?
Also I redirect you to MadWard's answer for the se passer alternative which is a very good option too.
That's kinda broad and you will have several translations depending on what you're asking. In a lot of them, the expression Se Passer would make a great fit. For instance:
How is your day going?
Comment se passe ta journée ?
How are your holidays going on ?
Comment se passent tes/vos vacances ?