Should I switch to PhD or graduate with a Master's? I am doing Master's in Applied Science in Civil Engineering. In my research I work with big data analysis which has gotten a fancy new name in past few years "Data Science". When I joined the master's program I didn't knew much about programming and had basic knowledge of statistical analysis. Over the period of about 2 years I learned a lot about data analysis in R language, developing data apps, creating interactive documents, etc. Although my research area had no direct relation with any of those things, I enjoyed learning them and using them in getting insights about data.  

On the other hand, this journey has been very frustrating because I could get very little useful knowledge for my research study. My 2 supervisors have been very supportive and both have asked me to continue my work and switch to PhD. 

One part of me long for getting out in the 'field' and have a 9 to 5 job with set amount of tasks everyday. But at the same time I am afraid to leave academia as this is all I've ever done in my career (worked as a Lecturer previously and now have graduate assistant positions). Money is another concern as I've not yet determined how much I would be able to get in scholarships/ grants during PhD.
I don't know how to keep myself motivated continuously during research, so there are always some days when I just don't do anything. I am really confused at this stage as to what should I do, complete my master's in next 4 months and graduate or go for a PhD. What are your thoughts/ experiences?
You shouldn't stick around for a PhD because you're afraid to do something else. A PhD is something that you should do because you're motivated to use the skills you acquire in the PhD in your later career (either as a researcher, or in a research-oriented field).

If you're not excited about being a PhD student, then it's not worth it in the long run to be miserable for several years of your life to obtain the degree. Moreover, because the PhD can limit your ability to take certain jobs—because of the perception of overqualification—if you're not motivated, don't do it.

In other words: Choose to do something because you want to be there—not because you're afraid to be somewhere else!