21 SAS reserve selection: how I'd prepare

1. Understand what you are applying to

21 SAS is a reserve unit. You keep your job, your family and your life, and you turn up to train — which is exactly what makes it hard. Nobody hands you a training block. You build the fitness on your own time, around everything else, for months, before anyone takes you seriously. If you only remember one thing from this guide, remember that the preparation is the test.

2. Get the standards from the source, then beat them

Fitness requirements change and are published by the Army. Get them from the official UK Special Forces Reserve pages, write them down, and treat them as your floor, not your target. Arriving able to just scrape a standard on a good day means failing it on a bad one, and every day on selection is a bad one.

3. Build an aerobic base long before you build speed

Everything I have ever done in endurance — my first marathon off three miles a week, four marathons in four weeks, twenty-seven hours on my feet in Madeira — came from the same boring thing: consistent, mostly easy mileage, week after week, for months. If you can't currently run comfortably for an hour, that is your project for the next eight weeks. Nothing clever. Just do not miss the runs.

My write-ups of how I built that base are here: preparing for a 42-mile ultramarathon, my first marathon and four marathons in four weeks.

4. Then get used to carrying weight, on hills

Running fit and hill-fit under load are different sports. Add weight gradually and add it late — the injuries I have seen came from people who bought a bergen and loaded it up in week one. Walk before you tab. Build the hours on hills before you build the kilograms in the bag.

5. Fix your feet and your kit early

The people who dropped out around me were rarely the least fit. They were blistered, chafed, badly fed or badly hydrated. Every long session is a chance to test boots, socks, layers and food. Nothing you use on the day should be new.

6. Train the part nobody trains

Long events are decided in the hours when there is no reason to keep going. That skill is trainable, and you train it by finishing sessions you wanted to quit — deliberately, in bad weather, tired, on your own. I have written about what that mindset actually looks like in having a lion's mentality and waking up at 4:30am.

7. A twelve-week shape

• Weeks 1–4 — base. Four to five easy sessions a week, one longer each weekend, no load. Build the habit and the hours before anything else.
• Weeks 5–8 — hills and load. Keep the easy volume. Add one weighted hill session a week and lengthen the weekend outing. Start recording how your feet, back and shoulders respond.
• Weeks 9–11 — specificity. Back-to-back weekend days on the kind of ground you will be tested on, in the kit you will be tested in, navigating for yourself.
• Week 12 — back off. Cut the volume, keep the frequency, sleep. You cannot gain fitness in the last week; you can easily lose the event.

8. Read my actual application

The two diary posts cover what happened rather than what should happen: part one, the application and part two, the ATC Pirbright weekend.

Questions?

Reply to the address you signed up with, or ask me anything at deepak@pearllemon.com. If you find something here that contradicts current Army guidance, tell me and I will correct it.