There is always more to do.
Right now, I have about 1000 unread e-mails in my inbox and I have a bunch of personal errands and projects around the house that I've been unable to get to.
One of the hardest things to learn is that if I don't get to all the e-mails, that's ok. You can't live your life in your inbox.
You have to put your personal priorities into your schedule or else other people will put theirs on yours. Each week, I take another look at my calendar... Did anything get on there that shouldn't be on there. I'll cancel if I have to.
I put in the things in my personal life that make me happy--bike rides to the beach to catch the sunset, kayak volunteering, softball, seeing my family--and work my job around them. That includes my health--working out and sleep.
Each week, I try to maximize the amount of time I spend doing things I look forward to, and minimize things done that I don't--things I accepted out of a misplaced sense of obligation or because someone else wants me to, even though I don't.
I'm a solo General Partner with no partner meetings. I don't take any meetings with founders where I don't think I can realistically get to a yes--and that means no quick 20 minute meetings. Small things and quick favors add up.
I don't do "office hours" at any accelerators--instead opting for a full meeting the one or two companies (if there is even one) that I really get excited about. You can't spend full time attention on things you're half interested in.
I don't do panel prep calls. If you asked me to speak on a panel, just tell me how you want the narrative to work and you run the panel. I know what to say because if I didn't, you wouldn't have asked me on. I'm happy to contribute two hours to be there, travel inclusive, but not two and a half or three because of the stupid prep call. Volunteering your time shouldn't cost you extra time.
I overindex for groups I can actively curate. Instead of going to happy hours sponsored by various vendors, I run one or two dinners per month where I can invite the attendees or get recommendations on who I should meet.
Synergies are important. The more you spend time with people who share interests with you, or where you can make your interests overlap, the more you'll get out of each moment.
It's not a perfect system, but it gets a lot more out of the clock than average.