I exercise in fits and starts, which is apparently worse for your body than not doing anything
I've started 30ds god knows how many times, same for c25k! And I started the insanity work out, but got ill and stopped!
ATM I'm back on the shred, but have just done a pilates/ballet work out cos the apprentice is on!
Also, I always gain in the first week of the shred and from what I've read, most people do! But it does come off and if you do measurements, they'll be going down even if your weights going up! Measurements and photos are key to the shred IMO!