Building your own 5/3/1 assistance programs
Wendler Log ships with eleven assistance templates, and every one of them is editable. Here is how to change them or build your own from nothing.

Step 1: open the assistance program list
Navigate to Assistance Programs from the main menu. This screen holds every program available to you: the stock templates and anything you have built.
From here you can edit a stock program in place, or create a new one. Assistance programs are not tied to a particular lift day; any program can be run after any main lift.
Once the list gets long, use search rather than scrolling. Reorder at the top lets you drag the ones you use most to the top, and programs are deleted from inside the program itself.

Step 2: edit the program
Each program has a name and a description. The description field is more useful than it looks. Put the rules of the program there: rep targets, when to add weight, what to do if you miss. It is the thing you will read six weeks from now when you have forgotten why you set it up that way.
Add movements with Add Exercise to Program. There is no cap on how many a program can hold. To change the order, use the options button at the top and choose Reorder Exercises.
Step 3: configure each exercise
Every exercise in a program can be set up independently:
- Custom weightlifting: weight, reps and sets
- Custom bodyweight: reps and sets, no load
- Same as main lift: mirrors whatever the day's main lift is
- Misc: no reps or sets, for things like swimming or conditioning
Loading is either a fixed number or relative:
- Set weight: an exact figure, for example 100 lb
- % of working weight: a percentage of that day's training weight, so 50% of a 100 lb military press gives you 50 lb
Percentage-based loading is what makes an assistance program scale with you. Set it once and the weights move as your main lifts move, instead of drifting further from the right load every cycle.
Each exercise also carries its own rest timer setting: whether the timer shows at all, and how long it runs.
Running it
During a session, move between exercises with the previous and next buttons at the bottom of the screen. Tap Complete Exercise to log what you actually did, so the assistance work ends up in your history alongside the main lifts rather than disappearing.