If anyone is looking for an easy way to get their heart rate up to max + exert themselves at max effort without doing anything too crazy, I highly recommend a C2 rowing machine. Set the program to a 5K (or 2K) and do the first half as a warmup, then go all-out for the second half. You'll easily hit your max heart rate and can try to sustain it for a minute.

Doing this only takes 10-20 minutes depending on the length of your warmup, and you'll be working your entire body + cardio + lungs. Just make sure you are using correct form - start slow before going all out.

I run and road bike, but rowing is easily the most efficient way to get into that HR zone quickly. You can do sprints but that's pretty hard on your legs if you aren't an active athlete. Rowing is low impact by comparison.