For a motto there are several snappier, more 'Latiny', phrases that you might consider. If you want to pursue a steadfast course — which is how I interpret your motto's purpose — you should probably indicate an objective in some way, for which I suggest the word propositum. There are many first-rank classical writers who use the word, adding an adjective or verb in some form to indicate the required persistence.
Caesar, for example, uses propositum tenere, 'to stick to the objective' (B. Civ. III, 42 : ubi propositum tenere non potuit, 'when he was unable to hold to his plan'). Rather more weakly, the verb habere is used instead of tenere, meaning merely to have a goal in mind. Suetonius (de Gramm. 24) has in proposito mansit, 'remained on his objective', meaning that [M. Valerius Probus] did not give up.
Using the first person singular, the form of verb to use in those phrases is either teneo, habeo or maneo. In a jussive sense, you might use the subjunctive: propositum teneamus is 'let us hold to our plan/task/objective' etc.
If you want your motto to state its intention as a matter of principle, you could choose an adjective, as in tenax ad propositum or tenax in proposito, 'tenacious in endeavour ' (the plural is tenaces). This is what I should prefer for myself.