Treats. Do any research on dog training methods and inevitably you will come across articles for and against using food in training.  I often hear people say dogs shouldn't do things because you have food with you, they should do it for praise alone.
The argument that comes up the most is - I don't want to have to carry treats with me all the time.
When used correctly - you don't.

I don't even use the word "treat" when discussing dog training and reinforcement. To me that word implies something special or indulgent. Using food in training is not an indulgence.
I don't want to get too technical but reinforcers can be primary (related to biology) - food, sex, water or secondary (have been paired with primary reinforcers) - toys, games, praise, touch (the list is not exclusive).
Here is where many people get confused. A reward is tangible. It can be primary or secondary - food, water, toy, tug, fetch. It's considered a reinforcer only if it serves to increase or strengthen a behaviour.
Because food is a primary reinforcer, when you pair it with praise, eventually the praise becomes reinforcing as well and you phase out the food reward. Praise alone, (without that pairing),  is often not enough to change behaviour for most dogs. (There are always exceptions)

I use food the same way I use the opportunity to engage in tug or a game of chase. If it's something the dog wants, it can be used as a reward to increase (reinforce) the likelihood of a behaviour occuring again . If the dog doesn't particularly love the reward, it won't work to reinforce the behaviour because the dog doesn't see it as reinforcing.
Lackluster response can often be traced back to lack of motivation - the reward is not seen as valuable enough to provide reinforcement (desire to perform).
I'm still trying to figure out why so many trainers and non trainers expect our dogs to do something just because we ask them to. Why is looking for a way to motivate our dogs seen as a negative? It should be the first thing we think of.

First scenario:  my employer asks for a volunteer to work over the weekend and says there is a bonus at the end. I volunteer and on Monday I receive a coupon for a fast food restaurant. That is not reinforcing enough for me to volunteer again in the future. My "volunteering behaviour" does not increase.
Second scenario: I volunteer to work the entire weekend and am presented with a day at the spa. That reward is something valuable to me and I am more likely to volunteer again when asked. My "volunteering behaviour" is strengthened and is likely to increase.

Whether using food or toys or walks or chase games, we need to think of whether or not it's something our dog will find reinforcing. You will have far greater success if you motivate rather than intimidate.