I think you have two questions here. One is about how to stay sane and balanced and growing spiritually in a stressful place. The second is about whether grad school is worth it.
To the first, I think there are a number of strategies. One is to have a small prayer group of people who will keep you grounded, another to have specific things like hobbies and exercise to de-stress, and a third is to create a whole community of people who support you. Having a church family and being able to step back and set your current crises in some sort of framework is important. Knowing what your boundaries are and having an end goal makes it more likely that you will be able to advocate for yourself and keep a level head when things are hard. These things are important in any life, and will help you whether you are in grad school or not.
But as to whether grad school is fun — I can’t speak for everyone. I can say that I myself and other grad students I knew experienced the passion of very focused work in a way that is hard to duplicate elsewhere. Many people form deep friendships and enjoy the bonds that joint hard work forms. Being in an institution where you are exposed to cutting-edge science and a wealth of ideas is an experience you will value even if the place you end up in is far removed from that.
I personally remember grad school as having both high highs and low lows. Among the highs for me were certain classes and student discussion groups and weekly symposia where I got to hear top scientists and connect with others doing research. I remember first discussing sustainable agriculture, learning how to teach better, hearing about forensic entomology, and seeing the data about climate change and ice in this wide array of intellectually stimulating meetings.
I spent happy evenings in the lab, looking down the microscope at an endlessly interesting world, hours in marshes collecting data and enjoying the outdoors. I formed a profound love of wetlands that to this day makes being in them transcendent. I met people from around the world. I got to know my neighbors in a couple of apartment complexes and had friends in a couple of churches where I formed deep ties. I married a kind man and had a wedding largely pulled together by grad students, family, and church. I had a child and took him to classes. These all remain the sparkling parts of a series of years where I was both in grad school and living my life, even though those same years were also difficult.
So while I wouldn’t go to grad school with the sole goal of having fun, many people in grad school do enjoy themselves while they learn skills and get the background to do something that they want to do.
We mostly hear and read about the stresses of graduate school — and they are very real. But that's not the whole story. The truth is that my years in graduate school were some of the best, and most fun, of my life. What a luxury to have time to learn about things you love and process them with inspiring mentors and intelligent friends, especially those who share your faith and can refine your thinking around the integration of faith, learning, and vocation.
I was in a marginal, interdisciplinary program that was perfect for me but made my stresses mostly financial. This led to greater reliance on God than ever before, and so it became a time of immense spiritual growth as well. That said, I am a strong advocate of getting some life/job experience, whether good or bad, before entering grad school. It will give you greater purpose and a framework for your learning that will always be both academic and personal.
At the end of the day, only you can know if graduate school is right for you at this time. The most important thing is hearing God's voice and discerning if he is calling you to this, at this time, or if the desire comes from somewhere else. Easier said than done, I know, but that is the key. I suggest taking quiet time away to silence the external (and internal) voices that may be distracting and focus on his voice, his word, and his love for you. If he calls, he will provide everything you need and his grace will be sufficient for the stresses and the joys.
I just finished teaching a class and my dissertation writing is going so slow, I'm despairing and I need to finish a paper — I've barely started — by the weekend. Fun??!! I ask in complete wonderment, what sort of creature be that? :)
Am I really qualified to answer that question? Questions in fact. For there are two I think: 1) Is grad school fun? 2) Is grad school too stressful to be able to seek Him first?
Now, I have loved being in grad school (and I have been here a long time!). I do a double-take every time I think of the sheer privilege I have of being given the time to think about questions that are important to society, that matter to me, that might (please God!) have some use to people I care about. Irrespective, just the luxury to think deeply! I am very grateful for that. And a platform to share my thoughts with others! What joy! So this is very much part of why grad school has been fun for me.
But it's also more obviously fun in terms of getting to hang out with remarkably interesting and very different sorts of folks. Folks that I might otherwise never have had the chance to meet as I went about my blinkered way through life, trying to make the next goal. Some of them, people like my advisor, for instance, are truly inspiring — they remind me what a gracious life looks like. And as for others — now I know which Korean drama to watch or which ale is the best or what classical music to listen to! Things that someone like me would have walked right past in another time. I have been learning, in a lived way, some of the sheer diversity of the human experience. I'm grateful for it.
In terms of stress. Hmm. Grad school can be stressful, undoubtedly. Often is. Though not terribly more so than other "serious" professions, I'd argue. A lot of the stress can come from pressures to be an "achiever" and from the solitary nature of a lot of grad school. But I think you are on to something when you talk about seeking Him first. For me, when things are rough — and of course they are from time to time, the paper isn't working out, colleagues seem to misunderstand, someone in power is being thoughtless — I remember that grad school has been very much part of seeking Him and His will. Not just His will for me, for His world. Stresses will come — but so long as they are not terribly self-focused (am I smart? am I sounding smart?), I think they are places where we learn, and we learn what we really value. And sometimes, we find that the things we value are very shallow and selfish — and we learn we might need to change. Which is all to the good, no?
Perhaps in asking about stress and fun you were referring to "work-life balance." I'm NOT the right person to answer that one, I'm afraid. Personally, I've not been very good about balance--I believe in all things in moderation, including moderation! :) Instead of trying to set up rules and disciplines, (though of course routines and rules are helpful--particularly when one is struggling to write one's dissertation!), I'd like to live a life of trying to follow Him. And He works in unexpected ways, does He not? And His sense of timing is adventurous, is it not? All of which would be terribly stressful, if we didn't also know that He loves us and He walks with us, in grad school and out.