I am knackered to the core. The thing is, it can't be good for the knees. All that extra weight. Call Dan. He knows about knees, given that his are always causing him gyp.
'Hulloo!' he says in his ironic hale-fellow-well-met voice.
'The thing is,' I begin, 'trekking up and down hills with 8 kilos on your back can't be good for the knees, can it?'
'No.' There's a pause.
'Oh. Is that the full pearl of your wisdom?'
'What are you actually doing?'
'Training for my Raleigh weekend.'
'Have you told them you've got one of their bikes? They might look on you more favourably.'
'So what have you got in your backpack?' asks Dan more helpfully.
'I can understand the water,' he says, 'but I think you've got quite a lot of cooking utensils and not a lot of fire-making equipment. I'd take out the frying pan and the lid, which isn't going to do you a lot of good without the pot, and put in a box of matches and a few logs for example.'
Dan puts on a more serious voice. 'What I've got from the physio is a whole load of exercises. No 1 is the Alexander Technique which is absolutely brilliant because all you have to do is lie on your back and put your head on a book. I asked if you have to absorb the information through the back of your head but it isn't that, it's just to support your head, and then you think yourself longer and stronger.'
'Longer and stronger,' I repeat slowly. 'I like that. And does it work?'
'Well wait, when you've done that, then you do your exercises, which is brilliant because they start with lying on your back. So, you pull your tummy in, and do some abominable crunches. Then you sit up with your legs out straight in front of you and wobble your knee caps about...'
'EEURGH!' I exclaim. 'Why?'
'Because you want to jiggle them back to the right place.'
'But aren't they in the right place anyway?'
'No,' he says witheringly. 'That's why you jiggle them about. It keeps them mobile.'
'But why aren't they in the right place?' I persist, sticking my legs out in front of me and jiggling.
'Because we're getting old and decrepit, and you more than me! So, then you stand up, legs apart, feet pointing slightly outwards, then you tighten up your fillet steaks...'
I burst out laughing. 'What does that mean?'
'It's the muscles on the inside of your spine - your inside loins... Then you have to squat down until your thighs are almost horizontal, stick your bum right out and you do that 30 times...'
I gasp out loud.
'But you might want to do it in three lots of 10. And Lize, it's brilliant. I could be on Operation Raleigh tomorrow. It is just cycling, isn't it?'
I let Dan go back to picking his courgettes. I must say, though, this is amazing and marvellous news. All is not lost. I'm going to lie down straight away.