Im 18 and have always had the problem of getting fully erect all the time. but just recently ive been getting lazy erections and not really hard ones.

Don't worry, yet.: Since arousal is largely psychological, you may be responding to life stress or lowering your libido by worrying about it. Pay less attention to the strength of your erection for a while. At 18, your libido will likely return to your previous state. Try skipping 1-2 days of masturbation and see if your erection returns. Make an appointment if this continues to be a concern.