It's eight o'clock in the morning and I've just come crashing through my front door dripping wet and with a face the colour of the inside of a beetroot.

The 'dripping wet' part might well be something to do with having been running on the sea bed just off the coast of Ghana. No, really - that's what my GPS watch says, anyway. I've got the pictures to prove it and everything:

It's nonsense, of course - the Ghanian coastguard frown on stuff like that these days - but it's also the risk you take when you put timing yourself down to a tiny sat-nav-esque device strapped to your wrist. Ever hear those stories about the drivers who end up on towpaths and over the edge of cliffs? GPS tracking is not an exact science.

My watch doesn't tell me where I'm going, but it does tell me where I've been. And anything and everything can muck up telling me where I've been. Take the day when I went out for a gentle 2km, only to look down after five minutes and discover that my average pace was 43km/hour [27mph in the English language].

After getting home and uploading my route, I discovered that somewhere in a local park I had suddenly flown in a perfectly straight line, Superman-style, to a town twenty miles away. This caused much amusement amongst my colleagues the next day, who have always known I'm not on this planet (I'm still waiting for my manager to buy me a cape).

An apparent spectacular drunken weaving through 10km one evening nearly resulted in me invoking the return-to-base warranty, but this is GPS all over. Bright sunlight? Sit on a wall for ten minutes waiting for it to find the satellites. Trees overhanging the pavement? Add another 100 metres to ensure you reach your intended distance. Tall buildings? Good luck with that.

Proper sat-navs tend to be a little more on the reliable side, simply because they need to be able to tell you exactly where you are right now. I've been tempted to go running with one, if only to see whether the patronising female voice says things like, "You can't seriously be out of breath already!", or, "Go home? I'm sorry, Jenny, I'm afraid I can't let you do that...".

TomTom released a multi-sport watch version of its wildly popular navigation system, with route planning and a 'Race Yourself' function in which you can see how painfully slow you went last time and suffer the private-yet-oddly-public humiliation of finding yourself going no quicker next time. Whether the woman ever says, "At the next exit, for goodness' sake, TURN ROUND!" is unconfirmed, but it would at least put Jillian Michaels into perspective.

What next for RunningJenny and the Magic Watch? Well, I'm just getting the screwdrivers out to see if it can be hacked to make me teleport. If anyone needs me, I'll probably be somewhere just off the coast of Ghana.

So, sitting at a computer all day does nothing for your waistline. As some of you may know, I went on a weight-loss tear in 2013 and turned into a very promising middle-distance runner.

Sadly, illness got in the way of everything and I wasn't really able to do much in the way of exercise. Things are on the way up again and it's time to get back to where I was, even if I am going to have to get there horribly slowly. In order to help myself as much as possible, I have introduced a variety of fitness options into my home. These are:

TWENTY QUID! Seriously, this is quite a bit of kit. It weighs a ton (which it would have to) and Wii Fit Plus has a ridiculous range of games including snowball fighting, ski jumping, a driving range, leading a marching band and beating the crap out of a robot. I am a decent snowball fighter, a professional ski jumper, a championship golfer, the world's worst band leader, and absolutely bloody terrible at beating the crap out of robots.

Check out my new exercise bike! I made it myself! (I only had to ask Twitter for help once.) It was a good price off Amazon and when it arrived I was pleasantly surprised to find it was magnetic, not belt-driven. It's pretty quiet and I get a nice view of the fish. Turns out you can get DVDs with stages of the Tour de France and such nonsense, so I might well do something silly like that one day.

Then there's this. Dear God, it's brutal. Not as brutal as the 45-minute ones they've put up for free on YouTube, however, so it seemed like a good idea in the event that I want to do a Jillian Michaels workout without dying multiple times. I am quite enjoying it.

Incidentally, I went to see Jillian on her 'Maximise Your Life' tour earlier this year, and she is hilarious.

Of course, you can't do any of this stuff without wanton consumption, hence huge box of goodies...

OK, I lied, you can do it without any of that. But it was an excuse to buy PowerBar Recovery chocolate milk drink, and I really needed an excuse.

Seriously considering a 'JennyFit' Twitter stream so that none of you have to hear about my fitness exploits when you would rather see me slobbing around playing games, so look out for that!