If you bought individual stocks, I'd avoid doing that going forward and go with the vanguard index funds using one of the 3 or 4-fund options FAHQSTV linked. Anything more than that and it gets too confusing for no real benefit (i.e. the Vanguard total stock index fund invests in large, medium and small companies, so there's no need to buy individual funds targeted to these). These funds are more stable than individual stocks on average.
Your situation is quite similar to mine (have a pension, plan to retire in ~20 years). There are two ways to think about your 403b in light of the pension (which I assume will cover your living expenses in retirement). How you may think is probably a mix of the two extremes, and should change as you get closer to retirement:
1. 100% stocks: I may not need this money at all or for a long time. Ignore the fluctuations and assume that stocks on average will go up for the next 20 years. If, when I'm about to retire, it's tanked for whatever reason, just rely on the pension until things recover.
2. 100% bonds: I'll be covered by the pension, this is mostly for an extra backup. Since it's a backup, I don't want to risk losing money when I may need it most (i.e. laid off before fully vested in the pension, etc). I'll take what I can get to stay above inflation, and not expect huge earnings. If in the end I get back out whatever I put in (plus inflation), I'll be happy.
The reason a savings account won't work for scenario 2 is inflation will eat it away slowly. Bonds generally keep up with inflation + a little extra (otherwise no one would bother to invest in them!) The ultra-safest ones are Treasury Inflation-Protected Securities, which are tied to inflation figures.
Based on what you said, you're probably going to want to go for more bonds than stocks.
Beyond all that nitty-gritty, things I've done to bolster against stuffing all my money under a mattress:
1. Ignore all the finance news, cooler talk about stocks, and social media. You will remember literally none of this in 15 years.
2. Don't use your colleagues as examples, since they probably haven't studied investing in any detail.
3. Check funds only once every 2-3 months, otherwise I get too obsessive about it. This also helps me conveniently forget my password in between, thus also decreasing my interest in re-checking. The only thing I do then is check what the balance between stock and bond funds is, and adjust future contributions to get it back in line.
4. Ignore ads for financial advisers. It's just too expensive a way of having someone else hold the purse strings so you don't dump all your savings on the floor and hide in a bunker with gold bullion!
