Over the years, I've noticed that any kind of productivity routine or hack I discover to increase focus always starts strong, but eventually plateaus. To maintain focus, I've found that having a "social contract" or "over-the-shoulder" buddy for self-accountability helps. These are the top hacks I've been able to stick with for some time now:
Hustl Mac App
I like this app because it's independent; you can get started without worrying about who your accountability buddy is or the technical setup. So, before I start any deep work like designing, I just turn Hustl on.
Focusmate.com
I use this less often because I'm on the free tier for now. But I do jump into this sometimes, especially when I'm on my Mac Mini setup (for which I don't have a license for Hustl).
Private Youtube Live
This probably takes the most time to set up but the ROI is worth the effort. Most of the time I often find myself working alone. However, sending links to close friends and family is fun because, suddenly, friends can join the YouTube chat and start interacting with me. If you're looking for a bit of unexpected fun while focusing on your work, I highly recommend this!