In the desert, the Israelites complained about the Lord's provision when they tired of its flavor. The every day provision of the Lord became a sour taste in their mouth. They wanted a new flavor, something different. They wanted the things for which they waited, they were ready for the promises to be fulfilled. They complained.
Promises aren't bad. The heart's desires aren't (necessarily) bad. I look at their situation and by process of elimination it's easy to find that what made the situation bad was their ingratitude followed by complaint. Manna miraculously appeared new each morning, but they got tired of it and grew ungrateful.
Personal application: though the current conditions of my life may not be exactly what I desire or am hoping and praying for, what refines me in faith and binds my heart to the Father's is praising him despite what I lack, whatever the lack. Responding to undesirable situations with ingratitude and complaint blinds me into thinking that God has not provided for me. It blinds me into thinking He's withholding things from me.
Ew. I'm embarrassed to be that entitled and self-centered.
I have everything I need, just not everything I want. Maybe He'll allow me to wait 40 years like the Israelites to discover that everything I need and everything I want can be found in Him, and the waiting is meant to give us rest when we trust in Him. Hopefully I'm a fast learner though, and I'll be able to live in my now with gratitude for what I have while also humbly, gratefully lifting up my dreams, hopes, and desires to Him, trusting Him with them as His timing is perfect. But I hope it never comes down to just wanting a new taste in my mouth, because clearly, there is purpose for every moment of my now because He still has me in it.