Usque conabor

I'm not sure I would ever use my old school motto in a speech; it doesn't seem to me to strike the right note. Mind you, mine, from the Perse school, was 'qui facit per alium, facit per se', that is to say who does things for others, does them for himself, an example of the cynical principle of enlightened self-interest. This Smilesian self-help tone fits the school nicely, for it was founded by Stephen Perse, 1547/8–1615, a  money-lender and property speculator.
There was another punning tag, used in the strapline of the school magazine  The Pelican, I think from Herodotus. I haven't been able to find the reference in the  Perseus digital library, but in translation it went, 'be counsellors of this world to me, O Persians' (hence Perseans).