Complain - To express feelings of pain, dissatisfaction, or resentment.
Have you ever deeply analyzed why you complain (assuming you do)? Have you ever, just once, asked yourself why you complain?
For each of us, I would contend our soul presumed to exist, rather than not exist. Once we came into existence, this fundamental question must be asked and answered fairly often: do I continue to exist or not?
Assuming the answer is to continue to exist, the next question becomes: should I exist well or not? This is what philosophy attempts to answer - how to love and live wisely.
We may have set expectations, but those expectations should be challenged and interrogated.
Complaining is an indication that our expectations and reality may be misaligned. It then becomes an exercise of determining if they can be aligned and how to go about doing so. All of us need to wrestle with this.
From a Stoic perspective, complaining usually means we are not living in agreement with Nature. Perhaps our desires and aversions have become too much. In this vein, Seneca wishes to provide some toughening to Lucilius.
Seneca tries to get at the root of Lucilius' discontent. The only real evil he is exhibiting is his complaining.
in all the evils to which you refer, there is really only one – the fact that you do chafe and complain ... I think that for a man there is no misery unless there be something in the universe which he thinks miserable.
Seneca tries to live by the idea of "live in agreement with Nature."
when everything seems to go hard and uphill, I have trained myself not merely to obey God, but to agree with His decisions. I follow Him because my soul wills it, and not because I must.
In this, we can see the sentiment which was first expressed by Zeno in the analogy of a dog being pulled by a cart.
They too [Zeno and Chrysippus] affirmed that everything is fated, with the following model. When a dog is tied to a cart, if it wants to follow it is pulled and follows, making its spontaneous act coincide with necessity, but if it does not want to follow it will be compelled in any case. So it is with men too: even if they do not want to, they will be compelled in any case to follow what is destined (LS 62A).
The thing 'up to us' is our attitude. Fate or Nature will drag us along regardless. But what is 'up to us' is our choice and perspective of the reality of the situation. Complaining may help drive out, to some extent, whether you can influence some circumstance or not, but to be perpetually complaining would be tantamount to acting like a dog being dragged unwillingly along with the cart.
If you choose to exist, there will be things which you must admit in your life. With existence, comes poor health. Seneca calls this a tax. You could either complain about the tax and still have to pay or, or you can simply pay it and get on with life. He writes,
It was disease of the bladder that made you apprehensive; downcast letters came from you; you were continually getting worse; I will touch the truth more closely, and say that you feared for your life. But come, did you not know, when you prayed for long life, that this was what you were praying for?
We are not genies in a bottle and get everything we wish for in life. That would be denying reality as it is.
"I wished to live, and at the same time to be immune from all ills."
Life is a battle. We are to be tried and tested - to use what is 'up to us' and to demonstrate that unique gift which we have: agency to determine our attitude and excellence of soul (or not).
Long, A. A., & Sedley, D. N. (January 01, 1987). The Hellenistic Philosophers.