Hello all.

I've been having some difficulty lately maintaining a chip lead, both live and online, throughout my recent sessions. I seem to do well early on in a session, but as the session progresses, I start to lose my profits and sometimes even bust out. It seems like the longer I stay in a session with a chip lead, I have the tendency to lose my profits. It's not like I switch up my game strategy or anything while I have a lead either. I don't play any hands that I shouldn't be playing just because I have a lead, and I really don't switch up my style either if I have a lead. It's almost like variance catches up with me later on in the session. For some reason, I tend to gain a chip lead early on, like within the first 20 or 30 minutes in a session, but I don't always like to cash out that early. I like to play for a couple hours or so. I usually set goals for myself with each session I play too. Number of hours I'd like to play, profit margin I'd like to achieve, not letting my emotions get the best of me during play, so on and so forth. Basically my question is, what should I do in order to maintain a chip lead that doesn't involve cashing out so early, or is cashing out a little earlier than expected the right way to go? 

Thanks for you're time.