Spinoza's argument against free will was not to say there was nothing to be done about changing one's experience and of those around you. Consider the following proposition:
Proposition 20:
This love for God cannot be tainted by emotions either of envy or jealousy, but the more people we imagine to be joined with God in the same bond of love, the more it is fostered.
Proof:
This love for God is the highest good that we can seek by the dictate of reason (by 4p28). It is common to all human beings (by 4p36), and we desire everyone to enjoy it (by 4p37). Therefore (by DOE23) it cannot be tainted by the emotion of envy nor (by 5p18 and by the definition of jealousy, for which see 3p35s) by the emotion of jealousy either. To the contrary (by 3p31) the more people we imagine to enjoy it, the more it must be fostered. Q. E. D.
Scholium:
We can in this same way show that there is no emotion that is directly contrary to this love by which this love can be destroyed; and therefore we can conclude that this love for God is the most constant of all emotions, and cannot be destroyed, insofar as it is related to the body, except with the body itself. We shall see later what nature it has, insofar as it is related to the mind alone. With this I have covered all the remedies for the emotions, or everything that the mind, considered in itself, can do in the face of the emotions. It is clear from all this that the power of the mind over the emotions consists:
First, in cognition of the emotions itself (see 5p4s).
Secondly, in the fact that it separates the emotions from the thought of an external cause which we imagine in a confused way (see 5p2 with the same 5p4s).
Thirdly, in the time, by which the affections related to things that we understand surpass those which are related to things that we conceive in a confused or mutilated fashion (see 5p7).
Fourthly, in the very many causes which foster the affections related to the common properties of things or to God (see 5p9 and 5p11).
Fifthly and finally, in the order by which the mind is able to order and connect its emotions with each other (see 5p10s as well as 5p12, 5p13 and 5p14).
But in order that this power of the mind over the emotions may be better understood, the first thing to note is that we call emotions great when we compare one person’s emotion with another’s and see that one person is assailed by a particular emotion more than someone else, or when we compare one and the same person’s emotions with each other and find that the same person is affected or moved by one emotion more than by another. For (by 4p5) the force of each emotion is defined by the power of the external cause compared with our own. The power of the mind however is defined by cognition alone, whereas its powerlessness, or passion, is estimated solely by privation of cognition, i.e. by that through which ideas are said to be inadequate. It follows from this that a mind is most acted on when inadequate ideas constitute its greatest part, so that it is distinguished more by being acted on than by acting. Conversely a mind acts the most when adequate ideas constitute its greatest part, so that, although there are as many inadequate ideas in the latter as in the former, it is still distinguished more by ideas that are related to human virtue than those that betray human powerlessness. Then, we should note that sicknesses of the spirit and misfortune mostly have their origin in an excessive love for something that is subject to many changes and that we can never control. For no one is anxious or worried about anything but what he loves; and offense, suspicion, enmity, etc. arise only from a love for things which no one can in truth possess. We easily conceive from this therefore what clear and distinct cognition can do in the face of the emotions, especially the third kind of cognition (on which see 2p47s) whose foundation is the very cognition of God. That is, insofar as they are passions, if it does not absolutely take them away (see 5p3 with 5p4s), it at least ensures that they make up a very small part of the mind (see 5p14). Then, it generates love for an unchangeable and eternal thing (see 5p15) which we in truth possess (see 2p45) and which for that reason is tainted by none of the faults that there are in ordinary love, but can always be greater and greater (by 5p15) and occupy the greatest part of the mind (by 5p16) and have broad effects upon it. And with this I have dealt with everything that concerns this present life. As I said at the beginning of this scholium, anyone will easily be able to see that in these few words I have covered all the remedies for the emotions, if he has paid attention to what we have said in this scholium and at the same time to the definitions of the mind and its emotions and finally to 3p1 and 3p3. It is now time therefore to move on to things that pertain to the duration of the mind without relation to the body.
Ethics: Proved in Geometrical Order (Cambridge Texts in the History of Philosophy) (p. 231 -236). Cambridge University Press. Part 5, Power of the Intellect, or Of Human Freedom — Spinoza