Don't fail to commit. Seneca, Epistles 2.20.3-6

Life is better when you approach it consistently, adopting attitudes that allow you to cultivate what you love and avoid what you hate without second-guessing yourself all the time. You will never see the fruits of long labor if you refuse to labor long. Remember, as you pursue what you love, that its final flower may not be what you imagined; that does not make it, or your love, worthless.

Observa te itaque, numquid vestis tua domusque dissentiant, numquid in te liberalis sis, in tuos sordidus, numquid cenes frugaliter, aedifices luxuriose; unam semel ad quam vivas regulam prende et ad hanc omnem vitam tuam exaequa. Quidam se domi contrahunt, dilatant foris et extendunt: vitium est haec diversitas et signum vacillantis animi ac nondum habentis tenorem suum. Etiam nunc dicam unde sit ista inconstantia et dissimilitudo rerum consiliorumque: nemo proponit sibi quid velit, nec si proposuit perseverat in eo, sed transilit; nec tantum mutat sed redit et in ea quae deseruit ac damnavit revolvitur. Itaque ut relinquam definitiones sapientiae veteres et totum complectar humanae vitae modum, hoc possum contentus esse: quid est sapientia? semper idem velle atque idem nolle. Licet illam exceptiunculam non adicias, ut rectum sit quod velis; non potest enim cuiquam idem semper placere nisi rectum. Nesciunt ergo homines quid velint nisi illo momento quo volunt; in totum nulli velle aut nolle decretum est; variatur cotidie iudicium et in contrarium vertitur ac plerisque agitur vita per lusum. Preme ergo quod coepisti, et fortasse perduceris aut ad summum aut eo quod summum nondum esse solus intellegas.

Watch yourself then, lest your clothing betray faults that your housing denies; lest you prove generous towards yourself but stingy to others, prudent at table but not when building your estate. Take just one rule to live by, and measure your entire life according to its standard. Some men contain themselves at home only to let loose and run riot abroad: this inconsistency is vicious, a sign that the mind wavers without yet holding a course. I will tell you right now the origin of such incontinence and incongruence in our affairs and plans: nobody infected with it admits to himself what he wants, and if he does manage to admit a goal, then he fails to persevere in what he has chosen, skipping from one thing to another instead. Nor is he content merely to change interests: always he returns to what he has deserted and condemned in the past, whirling about the same futile tasks without achieving any end. Thus, if I were to leave behind ancient definitions of wisdom and put the entire sum of human life into one new method, I would be content with the following. What is wisdom? To have wants and dislikes fixed, so that we consistently desire and avoid the same things. No fair making little exceptions for yourself, the kind that allow you to affirm the momentary rectitude of some passing desire. Only the really good things manage to please constantly. In the heat of the moment, men know nothing but fleeting desires, amongst which they find no firm decree to fix their fickle taste. Hence their judgment changes daily, wandering from one contradiction to another, and most waste their life playing pointless games. Press forward then, on the pathway you have already begun, and perhaps you shall achieve its summit, which need not lie where you think it does in this moment.