[Phanx]

You don't actually need to specify a type for the animation:

local timer = frame:CreateAnimationGroup()
 
local timerAnim = timerGroup:CreateAnimation()
timerAnim:SetDuration(60) -- how often you want it to finish
 
timer:SetScript("OnFinished", function(self, requested)
    -- requested = true if you used timer:Stop(), false if it finished naturally
 
    -- do stuff here
 
    self:Play() -- start it over again
end)
 
timer:Play()