because everyone else clearly knows what they're doing

I joined a gym.

I noticed that being in a gym is an extremely good way to make you feel inadequate. Luckily with your joining fee (which was, as one might expect, exorbitant) you also get three half-hour sessions with a personal trainer to get you started, as it were. This is good, because I basically have no idea what I'm doing. All I know is I want to get in shape.

I also haven't told any of my family - indeed I've gone to lengths not to tell them - and I'm not sure why.