I just finished up my PhD, and one thing I can tell you is that it sure
feels good when it's done! Seriously though, I have to say that these
last 6 years have been a wonderful part of my life. A lot of it
involved hard work, as you might expect. But also, coming from the
perspective of someone who worked for a while in the 'real world'
before going back to grad school, it was also a great period of
intellectual exploration. This was because, at least in my case, I
received a regular paycheck every month, without any strings attached.
What that meant was that I had complete freedom in deciding how my time
was spent. I could choose what I wanted to work on, and for how long. I
explored all sorts of different ideas, many of which didn't pan out,
and a few that did. In this exploratory process I gained valuable
experience and learned a lot from my mistakes.
However, for me the most worthwhile part was the satisfaction of
creating something new. It can be difficult and frustrating in doing
research at the edge of what is currently known, but it's also really
exciting when you figure out a little bit of the unknown territory.
After you write up your dissertation and research and put it out there
others, you can also take satisfaction in having made some
contributions to science and our general understanding of the world.
I don't know what particular reasons that you might have for pursuing a
PhD, but I would just conclude by saying that you should try to pursue,
in general, things that get you excited and that you find most
interesting.
Ask youself why do u want to enter grad school? Figure out what do u
want to acheive in grad school? Have a plan or at least an idea about
how to acheive your goal. The most importantly, be sure to talk to your
advisor and know what is in his or her mind. Try to work together with
your advisor and you are likely to finish your goal with joy.