Measuring your progress
For most of us, this means weighing - and that's where the spreadsheet is invaluable, as a way of recording and being accountable for your progress.
However, you don't have to be on the spreadsheet if you don't want to! And, importantly, if you are on the spreadsheet, you don't have to record your actual weight if you'd prefer not to. Instead you can index it - so you enter 100 on the spreadsheet tomorrow, and then for every pound you lose, you take one away. So if in week 1 you lose 4 lbs, you enter 96 next time.
Frequency of weighing
This can be a tricky one to negotiate for many people. It's entirely up to you how often you weigh, but one thing is important - weigh yourself only in the morning, naked, and after you've been to the loo! (If you don't have scales at home and are going to Boots, obviously don't do this naked ... 
). If you're weighing later in the day, all you're doing is weighing yourself plus what you've eaten and drunk that day.
Some people like to weigh daily, as they feel this keeps them on the straight and narrow. For me, not getting on the scales is a sure sign that I'm going off piste. But if you do this, you need to understand that your body weight fluctuates quite naturally day-by-day, so even if you are following the rules to the letter, your weight may still go up one day. This can be quite dispiriting, and can lead people to chuck it all in.
If you can't cope with this, then restrict your weighing to once a week - this means that any daily fluctuations should be straightened out.
There are a few different approaches to consider:
a) daily weighing, recording each day's weight (lots of people keep their own records, or have an app to do this). It can be really inspiring to plot your daily weight on a graph, to see the overall downwards shape of the line - this also helps you to understand your body's daily fluctuations
b) daily weighing, taking the average weight for the week and recording this
c) daily weighing, taking the lowest weight that you see on the scales as your score for that week
Entirely up to you which approach you take.
The scales don't always accurately measure weight loss!
Sometimes it happens that you know you've lost weight - you can tell by how your clothes fit, for example - but the scales don't reflect that (or even show a weight gain).
It can be useful to take your measurements as well as - or instead of - weighing yourself, as this gives you another insight into your progress.
A really good way to measure progress is to keep trying on an item of clothing that is currently too tight for you - this can be really motivating, when you start to realise that your clothes are fitting you better.
Above all though, don't panic if things don't appear to be moving every day, or quickly enough!
This isn't a race with other Bootcampers, and we have to remember it's a marathon not a sprint. The weight didn't all pile on in a couple of weeks, so it's also not going to disappear quickly.
The other thing to remember, which I've learnt from the 6 years of Bootcamp, is that weight loss isn't linear. It's very, very common to see days where there's no apparent loss, and then suddenly you'll drop 3lbs.