This is a pretty complex question! The answer is theoretical and not linear since every dog is different. But here are some loose ideas...
- Quality over quantity for 'boring' skills. Every dog has skills they really enjoy doing and skills they kind of balk at. If my dog hates sitting, I may only do one or two during an entire training session rather than drill it.
- Layer boring skills with fun skills. Understanding of reinforcement as a psychology term helps here because what you are actually doing is Premacking or using the second skill to reinforce the first. Behavior chain, whatever you want to call it.... But pretty much always do boring > fun. Do not do fun > boring. For example if my dog hates sitting but loves performing spin. I may ask for one sit, mark and reward with a treat, then ask for a spin. I will not ask for a spin then ask for a sit. Because I may inadvertently be punishing the spin with a sit and ruin the speed or enthusiasm of the spin.
- Reinforcement can be a series of events rather than a single delivery. The classic sequence for training is something like "Sit > dog sits > marker "good!" > reward with treat or tug. But you can layer in varied rewards (good job already throwing play into a training routine!) and also stack them.
- End on a high note. I always leave my dogs wanting more at the end of a training session. Don't train until your dog is bored with a particular skill or walking away. A super fun and engaged dog over a 2 minute session is better than a 10 minute session where the dog starts off awesome then is very distracted by the end.
There are many more things to consider. Like if a dog is very food motivated I can keep on using the same food but make it more exciting by changing my food delivery (some call it food play). If a dog is very toy motivated I may be able to chain behaviors and end with a big tug session, or use food for calm/low arousal behaviors instead. If a dog is at the maintenance level of a skill I might work on some acquisition/fluency level behaviors then reward with the 'easy' maintenance skill to make the dog feel like they are winning. If the dog is sensitive to touch then I might reward with touch in different ways - what happens when I grab the dog's snoot playfully? what happens if I do long smooth strokes on her back? So you can see that the possibilities are endless and the topic of motivation/reinforcement is extremely complex! Regardless what works for you and your pup, I hope you have fun training!