Delta opens as an empty notebook. No setup, no questionnaire, no plan wizard: the fastest way to learn it is to log one exercise, which is what this page does, start to finish. Two minutes of reading, tops.
Home has three big buttons. Tap Strength and you are in a workout; the clock at the top is already running. Nothing else is required and nothing is committed yet. If you tap it by accident, Discard erases all evidence.
Tap Add Exercise. The library is built for tapping, not typing: pick a group, tap the lift. Search is at the bottom if you want it, and the + writes a custom exercise if yours is missing. Once you have some history, a Most Used group floats your usual lifts to the front.
This is the one habit worth learning on day one: write set 1 first. Enter the weight and reps, then tap Add set. Every new set copies the line above it, so three sets of 95 × 5 is one fill and two taps, not three rounds of typing. (Adding empty sets first and filling each one by hand works too. It is just slower, and we have witnesses.)
The circle at the end of each row is the commit. Do the set in the real world, correct the numbers to whatever actually happened, then tap the circle. Locking starts the rest clock, which counts up so a long sit is visible, and flips color when you pass your target (2:00 by default; yours to change in Settings). Delta saves what you locked, not what you planned.
Ramping up with lighter warm-up sets? Press and hold a set row for the set menu and flag them as warm-ups: they stay in the log but out of your PRs and progress math. That menu and the rest of the quiet gestures live in quick tips.
Tap Finish and the workout is in the book. Home picks up the running tally: workouts, week streak, pounds lifted, all computed from exactly what you locked in. Next time you log the same lift, each set shows what you did last time, and the notebook starts doing the remembering for you.