Who should pursue a Ph.D degree? I am asking myself the question "Should I do PhD or should I leave academia and go for an industrial career?"

My life-goal is being a professor. And I love to do research. 

PhD is surely a bite that not everyone can chew.
But I wonder who can chew it?

I never was good at tests and exams. My BSc. GPA was 2.84/4.00 but finished my MSc. with 3.50/4.00

However, currently I am working on a conference paper and I feel like even that is too much for me. It has been nearly 3 months and still, the paper draft is to be improved (not the wording but the content).

I am surely a hard-worker but not always. Sometimes, I let go of my work and absorbed in other stuff (composing, amateur radio etc). If this period is too wide, I have to spend double effort to warm-up and remember where I left.

I don't know how things work in PhD. It usually is 5-6 years. It is the one of two most-challenging milestones in academic career (the other is getting the title Assoc. Prof).
Should I completely be a "nerd" and work on my thesis systematically (something I could never make in my entire life) or working periodically but with extra effort is still sufficient?

So, here's my question: If I say "I'm considering to do PhD" and ask your advice, what would you ask me? What kind of skills/characteristics do you look for a potential academician?

I know it is way too late for me to ask this kind of question, as a person who almost finished his master's degree. But better lose the saddle than the horse.
So, here's my question: If I say "I'm considering to do PhD" and ask
  your advice, what would you ask me? What kind of
  skills/characteristics do you look for a potential academician?


The first questions I would ask is: are you really interested in the subject? Can you imagine spending the next 5+ years thinking about pretty much nothing else?
Why do you want to do a PhD in the first place?


  However, currently I am working on a conference paper and I feel like
  even that is too much for me. It has been nearly 3 months and still,
  the paper draft is to be improved (not the wording but the content).


Now imagine the same thing but replace 3 month with 3 years.


  Sometimes, I let go of my  work and absorbed in other stuff.


This is also not very helpful for pursuing a PhD.

I think in most fields (that might be different for some fields of science) getting a PhD is only for people who want to do research. Apart from that it is only a waste of time and money. So the question you should ask yourself is not: Am I able to get a PhD? But rather: Do I want to get a PhD?

However, if you decided that you really want to give it a try: talk to someone from your university about it, maybe the supervisor of your thesis. Grades are not always a good indicator of the quality as a researcher.



EDIT:


  My life-goal is being a professor. And I love to do research.


That answers most of the questions.


  But I don't know if I'm capable of doing a Ph.D.


No one here can answer this question. You should try to talk to a professor at your university, the supervisor of your Master's Thesis, or someone who is doing research you are interested in. However, do not let your grades disencourage you, I know many students who had pretty bad grades but are great as PhD students and many excellent students who struggle with their research.