Although I think most prospective grad students have been told about the importance of picking a study/project that interests you, I think it's also really important to take some time to see how you interact with your supervisor and lab. These will be the people you work the closest with for the next several years, and help provide support to you in some of your toughest moments.
While it's true that you should work hard to reach your goal, burnout is real. Allow yourself to take breaks when needed; take a nap, play video games, and laugh at some memes. Life will feel less annoying.
Get involved in the community. Grad school is more than your research project; expand your contributions beyond your field of research and into the community where you are working.
Explore as many different topics and opportunities as you can, talk to lots of different people (who are interested in the same things, and different things!), and don't be afraid to ask for help to find the resources and supports that will help you succeed in what you want to do. When you're choosing an advisor, make sure that they will be able to provide you with the support and mentorship that you want and need, and that you are on the same page about academic and work expectations.
Words of wisdom for someone considering grad school...
My advice would be to not be afraid to try anything. Take any opportunities you have for new experiences because you never know what you will end up liking! If I had not tried a wide variety of courses during my time at the University of Guelph, I would not have discovered my interest in reproductive biology. Also, take any opportunity you can to speak with other graduate students; everyone is extremely friendly and always willing to lend a hand if you need it. Your peers are a great resource and are always willing to offer some advice on school, research, or life.
Guelph will provide you with a supportive and stimulating academic environment. My advisors provided me with the freedom to explore my research interests and the support and mentorship to help me become a better scientist. Their positive attitudes and confidence in my abilities allowed me to achieve success in my research goals. There are loads of clubs one could join (e.g. qualitative journal club, welfare and behavior group, dairy journal club, graduate student social committees, art clubs, etc.). In addition, my graduate program provided me with a safe and interactive social environment (e.g. intramural sports, city leagues, department socials).
For my non-native English-speaking friends, there is a plethora of support from the international office! In addition, the library provides lots of writing and technical support!
