I take 10 mg of lisinopril daily. Wondering how dangerous it is if I forget to take it every once and a while?

Not detrimental. It takes a tremendous amount of dedication to stay on a medical regimen every day of your life! It is important that med be taken as prescribed, but we all forget here and there. For lisinopril, it is not detrimental if you missed a dose especially if you have been taking it regularly (you have a good, steady level of it in your body already) and that your pressure is under good control. Good luck.
Timing of lisinopril. Lisinopril (l) is best taken daily. It works by remodeling (r) the endothelium (e) (lining) of the arteries to lower bp. This r takes about 2 weeks. L also reduces proteinuria which is important. Once the e is r, the BP is lowered. If l is stopped, the BP rises slowly back to is level before l was started. You miss an occasional dose of l and I cannot recommend you do so on a regular basis.