Quotes, in this context, are used to identify speech. If we are discussing what someone said, quotes are used when the enclose words are an exact rendering of what was said, but are not use when only the sense of what someone said is conveyed.
Patrick Henry said, "Give me liberty or give me death!"
Patrick Henry said that he wanted either liberty or death.
The second sentence conveys the content of what was said, but is not offered as an exact (sometimes called direct) quote.
In your examples, there is no actual speech. There is also no suggestion that the reader (or listener) actually say the sentences that reflect the content of the instructions. They would be better expressed as
Consider what will you do next year.
Think about what your plans are for the holiday.
Neither sentence is actually a question. Alternative forms could take quotation marks if they expressly represented a literal question, such as
I ask you to consider this: "What will you do next year?"
You should think about one thing "What are my plans for the holiday?"
Both suggest actual exact speech (even if it is to rendered only in your mind).