The amount you originally chose was almost certainly right for that exact moment — comfortable, realistic, sustainable given what you were earning at the time. The problem is that life doesn't stay still just because your Direct Debit does. Pay rises happen. Jobs change. The financial breathing room you have a decade from now rarely looks like the breathing room you have today.

Then there's inflation, working against you quietly in the background. Something that cost £100 back in 2016 costs roughly £140 today — and a fixed contribution loses exactly that kind of ground every year it stays unchanged. A figure that felt meaningful ten years ago is worth noticeably less in real terms now, even though the number on your bank statement hasn't moved at all.

The better way to think about it: your monthly contribution should evolve alongside your income and your goals, not sit frozen as a number you picked once and never revisited.

It's easy to assume only a dramatic change in what you invest will actually move the needle. In reality, small, steady increases can do an enormous amount of the work.

Picture two people, both starting out investing £200 a month:

Assuming both portfolios grow at 5% a year after fees, here's where they end up after two decades:

Hypothetical example for illustration only — assumes 5% annual growth after fees and isn't a forecast of any specific investment.

Investor B ends up around £14,000 better off — and notice how small the actual increases were along the way. In year two, the contribution rises from £200 to just £204. By year twenty, it's crept up to roughly £290 a month. None of those individual increases would register at all. Stacked up over two decades, though, they're worth nearly £14,000. Market performance tends to steal the spotlight, but how much you actually put in is usually the biggest lever you control.

A pay rise is, hands down, the simplest trigger for increasing your contribution — because you're not being asked to carve the money out of a budget that already works without it. Say your salary rises 4%. Putting half of that, say 2%, toward your investments still leaves you the other half to enjoy, while quietly keeping your investing habit growing in step with your income. Because that money never touched your everyday spending in the first place, an increase timed this way barely registers as a sacrifice — unlike trying to find extra savings inside a budget you're already used to living on.

Do this consistently, and your investments keep pace with your earnings, rather than slowly shrinking as a share of your income year after year.

The simplest way to actually follow through is to remove yourself from the decision in the moment. A few ways to do that:

None of these rely on willpower at the time — which is exactly why they tend to actually happen, year after year, in a way a vague "I'll top it up later" intention rarely does.

If you're already contributing to an investment every month, you're already ahead of a large number of people who never quite get round to starting. The next step isn't necessarily a dramatic jump in what you invest. It's building the habit of checking that number and nudging it up whenever life gives you the room.

Starting early gets most of the credit in investing folklore. But making sure your contributions keep pace with your life — your income, your goals, the cost of living — matters just as much. And it's precisely the kind of thing that's easy to know and easy to forget, which is usually where an annual review with someone keeping an eye on it for you earns its keep.