I am not talking about consequences, such as in "I can't find my wallet, I must have lost it" in which case I think something like ~に違いない could be used. Rather, I would like to know how to express that something "must be + adj" because of some reason.
Example 1: We must be strong (for example because the times are tough).
Example 2: The transition must be harmonious/peaceful
My guess is that some verb conjugated in the "なければならない" form should be used, with the verb depending on the situation.
Example 1: 強くでいなければならない.
Example 2: 推移は...に行わなければならない.
Which makes me realize I also would like to know what's a good word for "peacefully/harmoniously" in this case. Notice that here I'm thinking of an abstract transition from one state to another such as could be changing a job or habit, rather than a concrete physical transition.
Anyway, I am really not very confident that my attempts make sense (if they are grammatically correct at all) so even though somehow I feel this is probably something quite basic, I'd appreciate some help. Thank you.