Is it possible to have a healthy work-life balance as a professor?
To add to the existing answers:


  Can you be a (relatively) “lazy” professor and still hold a position?


Yes. Once you have a (tenured) position, you can probably be rather lazy and still hold onto it.


  So do you think that it is possible to have a healthy work-life balance as a professor or is that approach to a professorship, at least early on, not realistic for the modern market place of academia?


The part about "at least early on" is crucial here. While you can (and some do) gear back a bit once you have tenure, you don't generally get into this position by being lazy. Academia is very competitive (as other answers have indicated), and to end up on top of a hiring pile you will need to be considerably more accomplished than your peers. For most people, being more accomplished means that you will have to put in the hours (and even then there are no guarantees, of course).

Generally speaking, the description of how you envision the job indicates more interest in a teaching-focused, low-research position. This is perfectly appropriate. Competition for such jobs may be a bit lower than at the top research schools, but is (at least in most areas of the world) still high enough that a truly lazy person will not see any offers.

However, and this is important, it is my observation that professors at teaching-oriented schools do not actually work less than their counterparts at research schools. In teaching-oriented schools, the teaching load will evidently be (much) higher, and individual students may be weaker (meaning that they often need more time-consuming direct support). TAs are common in research schools, but often rare or completely unknown in teaching-oriented schools. All in all, from talking to colleagues at teaching-oriented schools, I got the impression that they are putting in at the very least comparable hours to me (often for lower status and salary). You should not fall into the trap of envisioning a teaching position as the same as a research-focused professorship, with the only difference being that nobody cares if you do research.

It is still possible to have a work-life balance (in both, research and teaching focused positions), but it will require some planning and working smart and dedicatedly. It is unlikely that you will manage to get tenure by actively being lazy.