What are your favorite ways to track long term challenges like 2021 miles, pullups, etc. in a year? Paper, spreadsheet, app, other?

I like Strava for cardio but you can't really track climbing and weight training well. Also I like tracking specific things like average Heart Rate, max Heart Rate, number of pitches climbed, etc. which no one app encapsulates. I've settled with basically a more techie version of a spreadsheet -- I use Notion with two databases, one for tracking everything I want for any one workout (run, climb, hike, bike, weights) and then a second one which is really just a "roll up" of the first one, where I do planning and track weekly/monthly/yearly progress. I use Notion for tracking other things so I was already familiar with the software and set it up in a day or two. For weight training I use pen and paper, and like Hans said I just pull out last year's notebook to see what I was lifting.

I've been going old school and just doodling notes on a wall calendar. It's fun to encouraging to watch the month fill up with activity, but also easy to see the days I missed.

Coros is amazing for recording this stuff.

Doing a mix here…

I use habit tracker app for things like "do x (at least) y times a week", and also have a spread in my bullet journal for the full year, marking days I went running, climbing, training with colored dots.

Running I track with an another app, as I do biking.

Other challenges I note down in my journal or on the tally sheet (online & hardcopy as a backup).

Honestly, I use the dht sheet. But I wouldn't be tracking my workouts if it wasn't for the challenge. I also just signed strava which integrates with my Coros watch. The watch is GREAT for tracking and has its own software. At the end of the year you get a report from the year with your stats (I'm guessing you can get them anytime).