The only way to progress effectively is to gamble at the market, and there seems to be a 50% chance of getting nothing at all. I rolled 3 nothing's in a row at the market.
There needs to be other ways to progress; promotions at work, stamina upgrades, and so on....
Also, the muscle growth pics seem to be out of order? The first pic of her is incredibly shredded and it seems like she gets less buff with the other upgrades. I only made it to about 200 muscle before I quit.