I'm happy or I feel like happiness
In this particular case the person feeling happy is gathered from context. If I express it, or declare it, I am the one who must be happy. The second particle is ku which means 'to be in a stance for' barely.
I'm ready to speak to you
To express you are ready to engage some activity. It also depends on the context, but in this case the one who is ready is the same as the subject of the verb. There is a subtle difference between the two of the above expressed declarative particles. For example to express to different things about one verb
I feel like eating or I'm hungry/I want to eat
I'm ready to eat
The first could be understood to mean 'I'm hungry' or 'I'm in the mood to eat (something)' this relies heavily in context, while the second can be said when you take your sit at the table and want the feast to commence, or maybe when you want someone to start serving the food. You can always add evidentials to these. The last declarative particle is shu this is not really a particle in the same sense as the others, but Kareyku grammarians still do group it as a declarative particle. It means completion of an action or to do something until the end. This is mostly used when ordering something to be carried through.
Eat up! or eat it all!
You can hear a mother say to her child. Needless to say it has some other uses, such as if someone wants to tell you something but takes a lot to finally say what he means to say, you can always snarl
ikan tanada shu!
1st say-3T DECL
Tell me already!
In this sentence the meaning is the same as the translation, and you can thus see how important context is in Kareyku specially in relation to the declarative particles which are widely used. This is the same kind of particle you use in the respectful greeting pendibeki wilé ladome, the evidential always attached to the declarative particle.