flexibility is a strength
If you know me, you know I am fiercely devoted to my routines in an effort to maximize my time. Deviation from these was something I had to get used to during the last 5 years - going outside of my comfort zone, in a way - because usually, being flexible will do you more favors than you think.
Let's take boundaries as an example (a hot button word for armchair therapists these days). When I began, I swore I'd never be the student who was working overtime every weekend. I saw way too many senior students burning out and pulling long days every Saturday and Sunday, and I wanted to avoid that as much as I could. Most senior students will also tell you that you have to have a good work/life balance with your time. (Also, do be careful not to fall into competing in the Suffering Olympics.) I would get upset if I was still in the lab at 7pm, and complain about how this was cutting into my personal time.
What I wish I knew is that with science, sometimes those boundaries are not going to work. Instead, it's up to you to decide what is or isn't possible, or what will do you a net good for whatever your goal is. I learned this when writing my fellowship applications. I mean, the NIH has the same deadlines every year for grants - so if you're still polishing edits on your application the Saturday before a Monday deadline, so be it. If your Western turns out like a Rorschach test on a Friday and you really want this blot for a meeting on Monday, then you might want to rerun it over the weekend. Sometimes, your work is making the decisions for you. I had to learn that this was okay, especially if I had to make a deadline. The unfortunate truth was I wasn't going to finish my PhD on time if I refused to ever touch work after 5pm on Friday.
Balance, of course, is the answer, and that looks different for everyone. Some people might love working 9am-8pm 7 days a week. Some people don't. And sometimes, you have to be willing to change with the seasons. Whenever I'd have an application deadline or a presentation coming up, I knew to keep my weekends clear to write, edit my slides, or practice talking. In the month leading up to my thesis submission, I cleared all my weekends and mentally prepared myself to be writing every single day, because that's what I needed to do. If I was in a good writing groove at 7pm on a Saturday, I took advantage of it and kept going. In exchange, though, if there was nothing pressing I'd take both Saturday and Sunday off, or maybe head in to change cell culture media on Saturday and then not touch anything work-related on Sunday.
I'm not telling you that you have to continuously pull out all the stops and fire on all cylinders constantly. Be aware of your own symptoms of burnout. But what I am saying is that you have to be able to roll with the punches, as my PI would say. Making the best use of your time can mean leaving at 5pm sharp on Wednesday to make it to a workout class, and it can also mean spending 5 hours in the library on a Saturday to get some work done. Both things are okay! And that's a fact I wish I understood sooner, so I would have less resentment during the tougher times of my PhD.