When your Tamagotchi won't play games,
It's probably because their weight is good enough. You don't need to play any more games! You can think of it as 'tamagotchi too tired'. However, if you would like to play more games, you can just feed it a snack to make its weight increase.
To get training bars,
When your tamagotchi beeps, and you've checked the health meters and everything is normal, and your tamagotchi is just walking around like usual, give it a time-out. This increases one traning bar.
When your Tamagotchi beeps and it is turned backwards with a little symbol on the top right, it means it needs attention. Just praise it and it will increase one training bar.
When your tamagotchi is crying, praise it. This will increase one training bar.
When you connect with another tamagotchi and give gifts to the other tamagotchi, when it gives something bad and comes back with a silly face, give it a time out. This will increase one training bar.
Usually when you give your tamagotchi a time out, one happiness heart goes down. So remember to get that heart filled back up!