Give it a few minutes (five minutes maximum) a couple of times a day and your puppy will be trained quickly.
Remember your puppy is a baby and cannot take long periods of training. As she gets older you can extend the training time appropriate to age.
Put your puppy on a leash and start walking. It seems like it would be helpful for your puppy to walk slowly, but the opposite is true. A brisk walk does a better job of getting and keeping his attention. Take a few steps, stop, and as soon as your puppy sits, click and give him a treat. Turn and walk in another direction. Walk a few strides, turn left, then stop. Repeat but turn right this time. Now mix it all up however you want.
If you lose his attention, do any or all of the following.
Stop and wait for him to sit
Turn and go a different direction so he has to pay more attention
Change the game into a recall and excitedly call his name while backing up
Consider if you’ve done enough for the day and maybe his little brain is getting tired.
Only start with a few minutes at a time. Puppies have short attention spans, and you can add duration as he gets older.