Your current nos and maybes are paving the way for your future yeses. 

Saying yes because it is easy, safe, expected or demanded leads to future nos and maybes.

Saying no or maybe now because you know it will increase and enhance your ability to say yes to the right things later is challenging, risky and difficult but more than likely going to lead to sustainability, expansion and success. 

Saying yes religiously will hold you back, lead to staleness, bound you to today's opportunity not tomorrows and frustrate you.