Assuming that the shit is going to hit the fan in five weeks time (in the physical fitness sense) and am currently able to do a bft smoothly in 9:50 mins, exactly how much fitter do you think you can get in a mere 5 weeks?
Don't go mad, 3 decent runs a week (tailored for BFT distance 1.5 miles fast 1.5 steady) you'll get it to maybe 9.30. Doesn't necessarily mean you're fitter - just means you can run 1.5 miles faster than before.
If you're doing anything with weight, you're better off getting your core strength up (sit ups, press ups, v sits) so you're less likely to injure yourself. Similarly get your ankles knees and hips used to carrying extra by doing some medium/fast walking with 20-30lb (on grass not concrete if you can).
You can't do much to increase fitness vastly at this stage, and your body will react to any increase in pace once course/whatever starts so you have to rely on your inherent fitness. The key thing is to avoid injury, good preventative measure - stretch. Stretch throughout the day. Do something called PNF(?) stretching - can;t remember the proper name but it's basically stretch, hold, relax it slightly, stretch again and hold it a bit longer. Works a treat, supple people don't break.
I'm 27 at the minute and am mentally reasonably tough (hahaha..Cough, splutter). I ask as "assessment" for the TA version of 264 sigs kicks off shortly - And I have found "pre" assessment to be quite taxing as it stands. A nice increase it fitness would be handy, if nothing else simply to make me feel more confident about the whole thing
Ah, selection! There is no substitute for time spent on the hills. Get yourself down there at weekends. Run yourself ragged. Take some holiday or sickies. If you can squeeze in 14-15 days on the Beacons/Black Mountain/Elan Valley in that time you will significantly increase your chances.